Migrate to govendor to avoid limitations of godep

- over the course of a project history every maintainer needs to update
  its dependency packages, the problem essentially with godep is manipulating
  GOPATH - this manipulation leads to static objects created at different locations
  which end up conflicting with the overall functionality of golang.

  This also leads to broken builds. There is no easier way out of this other than
  asking developers to do 'godep restore' all the time. Which perhaps as a practice
  doesn't sound like a clean solution. On the other hand 'godep restore' has its own
  set of problems.

- govendor is a right tool but a stop gap tool until we wait for golangs official
  1.5 version which fixes this vendoring issue once and for all.

- govendor provides consistency in terms of how import paths should be handled unlike
  manipulation GOPATH.

  This has advantages
    - no more compiled objects being referenced in GOPATH and build time GOPATH
      manging which leads to conflicts.
    - proper import paths referencing the exact package a project is dependent on.

 govendor is simple and provides the minimal necessary tooling to achieve this.

 For now this is the right solution.

internal/github.com/facebookgo/stats/license

@@ -0,0 +1,30 @@
+BSD License
+
+For stats software
+
+Copyright (c) 2015, Facebook, Inc. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+
+ * Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+ * Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+ * Neither the name Facebook nor the names of its contributors may be used to
+   endorse or promote products derived from this software without specific
+   prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

internal/github.com/facebookgo/stats/patents

@@ -0,0 +1,33 @@
+Additional Grant of Patent Rights Version 2
+
+"Software" means the stats software distributed by Facebook, Inc.
+
+Facebook, Inc. ("Facebook") hereby grants to each recipient of the Software
+("you") a perpetual, worldwide, royalty-free, non-exclusive, irrevocable
+(subject to the termination provision below) license under any Necessary
+Claims, to make, have made, use, sell, offer to sell, import, and otherwise
+transfer the Software. For avoidance of doubt, no license is granted under
+Facebook’s rights in any patent claims that are infringed by (i) modifications
+to the Software made by you or any third party or (ii) the Software in
+combination with any software or other technology.
+
+The license granted hereunder will terminate, automatically and without notice,
+if you (or any of your subsidiaries, corporate affiliates or agents) initiate
+directly or indirectly, or take a direct financial interest in, any Patent
+Assertion: (i) against Facebook or any of its subsidiaries or corporate
+affiliates, (ii) against any party if such Patent Assertion arises in whole or
+in part from any software, technology, product or service of Facebook or any of
+its subsidiaries or corporate affiliates, or (iii) against any party relating
+to the Software. Notwithstanding the foregoing, if Facebook or any of its
+subsidiaries or corporate affiliates files a lawsuit alleging patent
+infringement against you in the first instance, and you respond by filing a
+patent infringement counterclaim in that lawsuit against that party that is
+unrelated to the Software, the license granted hereunder will not terminate
+under section (i) of this paragraph due to such counterclaim.
+
+A "Necessary Claim" is a claim of a patent owned by Facebook that is
+necessarily infringed by the Software standing alone.
+
+A "Patent Assertion" is any lawsuit or other action alleging direct, indirect,
+or contributory infringement or inducement to infringe any patent, including a
+cross-claim or counterclaim.

internal/github.com/facebookgo/stats/readme.md

@@ -0,0 +1,4 @@
+stats [![Build Status](https://secure.travis-ci.org/facebookgo/stats.png)](https://travis-ci.org/facebookgo/stats)
+=====
+
+Documentation: https://godoc.org/github.com/facebookgo/stats

internal/github.com/facebookgo/stats/stats.go

@@ -0,0 +1,166 @@
+// Package stats defines a lightweight interface for collecting statistics. It
+// doesn't provide an implementation, just the shared interface.
+package stats
+
+// Client provides methods to collection statistics.
+type Client interface {
+	// BumpAvg bumps the average for the given key.
+	BumpAvg(key string, val float64)
+
+	// BumpSum bumps the sum for the given key.
+	BumpSum(key string, val float64)
+
+	// BumpHistogram bumps the histogram for the given key.
+	BumpHistogram(key string, val float64)
+
+	// BumpTime is a special version of BumpHistogram which is specialized for
+	// timers. Calling it starts the timer, and it returns a value on which End()
+	// can be called to indicate finishing the timer. A convenient way of
+	// recording the duration of a function is calling it like such at the top of
+	// the function:
+	//
+	//     defer s.BumpTime("my.function").End()
+	BumpTime(key string) interface {
+		End()
+	}
+}
+
+// PrefixClient adds multiple keys for the same value, with each prefix
+// added to the key and calls the underlying client.
+func PrefixClient(prefixes []string, client Client) Client {
+	return &prefixClient{
+		Prefixes: prefixes,
+		Client:   client,
+	}
+}
+
+type prefixClient struct {
+	Prefixes []string
+	Client   Client
+}
+
+func (p *prefixClient) BumpAvg(key string, val float64) {
+	for _, prefix := range p.Prefixes {
+		p.Client.BumpAvg(prefix+key, val)
+	}
+}
+
+func (p *prefixClient) BumpSum(key string, val float64) {
+	for _, prefix := range p.Prefixes {
+		p.Client.BumpSum(prefix+key, val)
+	}
+}
+
+func (p *prefixClient) BumpHistogram(key string, val float64) {
+	for _, prefix := range p.Prefixes {
+		p.Client.BumpHistogram(prefix+key, val)
+	}
+}
+
+func (p *prefixClient) BumpTime(key string) interface {
+	End()
+} {
+	var m multiEnder
+	for _, prefix := range p.Prefixes {
+		m = append(m, p.Client.BumpTime(prefix+key))
+	}
+	return m
+}
+
+// multiEnder combines many enders together.
+type multiEnder []interface {
+	End()
+}
+
+func (m multiEnder) End() {
+	for _, e := range m {
+		e.End()
+	}
+}
+
+// HookClient is useful for testing. It provides optional hooks for each
+// expected method in the interface, which if provided will be called. If a
+// hook is not provided, it will be ignored.
+type HookClient struct {
+	BumpAvgHook       func(key string, val float64)
+	BumpSumHook       func(key string, val float64)
+	BumpHistogramHook func(key string, val float64)
+	BumpTimeHook      func(key string) interface {
+		End()
+	}
+}
+
+// BumpAvg will call BumpAvgHook if defined.
+func (c *HookClient) BumpAvg(key string, val float64) {
+	if c.BumpAvgHook != nil {
+		c.BumpAvgHook(key, val)
+	}
+}
+
+// BumpSum will call BumpSumHook if defined.
+func (c *HookClient) BumpSum(key string, val float64) {
+	if c.BumpSumHook != nil {
+		c.BumpSumHook(key, val)
+	}
+}
+
+// BumpHistogram will call BumpHistogramHook if defined.
+func (c *HookClient) BumpHistogram(key string, val float64) {
+	if c.BumpHistogramHook != nil {
+		c.BumpHistogramHook(key, val)
+	}
+}
+
+// BumpTime will call BumpTimeHook if defined.
+func (c *HookClient) BumpTime(key string) interface {
+	End()
+} {
+	if c.BumpTimeHook != nil {
+		return c.BumpTimeHook(key)
+	}
+	return NoOpEnd
+}
+
+type noOpEnd struct{}
+
+func (n noOpEnd) End() {}
+
+// NoOpEnd provides a dummy value for use in tests as valid return value for
+// BumpTime().
+var NoOpEnd = noOpEnd{}
+
+// BumpAvg calls BumpAvg on the Client if it isn't nil. This is useful when a
+// component has an optional stats.Client.
+func BumpAvg(c Client, key string, val float64) {
+	if c != nil {
+		c.BumpAvg(key, val)
+	}
+}
+
+// BumpSum calls BumpSum on the Client if it isn't nil. This is useful when a
+// component has an optional stats.Client.
+func BumpSum(c Client, key string, val float64) {
+	if c != nil {
+		c.BumpSum(key, val)
+	}
+}
+
+// BumpHistogram calls BumpHistogram on the Client if it isn't nil. This is
+// useful when a component has an optional stats.Client.
+func BumpHistogram(c Client, key string, val float64) {
+	if c != nil {
+		c.BumpHistogram(key, val)
+	}
+}
+
+// BumpTime calls BumpTime on the Client if it isn't nil. If the Client is nil
+// it still returns a valid return value which will be a no-op. This is useful
+// when a component has an optional stats.Client.
+func BumpTime(c Client, key string) interface {
+	End()
+} {
+	if c != nil {
+		return c.BumpTime(key)
+	}
+	return NoOpEnd
+}