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.

buildscripts/updatedeps.sh

@@ -1,34 +0,0 @@
-#!/usr/bin/env bash
-#
-# Minio Client (C) 2015 Minio, Inc.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-#
-
-_init() {
-    godeps="Godeps/Godeps.json"
-    filter="minio/minio"
-}
-
-update() {
-    for dep in $1; do
-        godep update $dep;
-    done
-}
-
-main() {
-    deps=$(env grep ImportPath ${godeps}  | grep -v ${filter} | cut -f2 -d: | sed -e 's/,//' -e 's/^[ \t]*//' -e 's/[ \t]*$//' -e 's/\"//g' | tr '\n' ' ')
-    update ${deps}
-}
-
-_init && main "$@"