signature: Use a layered approach for signature verification.

Signature calculation has now moved out from being a package to
top-level as a layered mechanism.

In case of payload calculation with body, go-routines are initiated
to simultaneously write and calculate shasum. Errors are sent
over the writer so that the lower layer removes the temporary files
properly.

pkg/xl/acl.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 package xl
 
 // BucketACL - bucket level access control

pkg/xl/bucket.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 /*
  * Minio Cloud Storage, (C) 2015 Minio, Inc.
  *

pkg/xl/common.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 /*
  * Minio Cloud Storage, (C) 2015 Minio, Inc.
  *

pkg/xl/config.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 /*
  * Minio Cloud Storage, (C) 2015 Minio, Inc.
  *

pkg/xl/definitions.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 /*
  * Minio Cloud Storage, (C) 2015 Minio, Inc.
  *

pkg/xl/doc.go

@@ -0,0 +1,3 @@
+// +build ignore
+
+package xl

pkg/xl/encoder.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 /*
  * Minio Cloud Storage, (C) 2015 Minio, Inc.
  *

pkg/xl/errors.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 /*
  * Minio Cloud Storage, (C) 2015 Minio, Inc.
  *

pkg/xl/heal.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 /*
  * Minio Cloud Storage, (C) 2015 Minio, Inc.
  *

pkg/xl/interfaces.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 /*
  * Minio Cloud Storage, (C) 2015 Minio, Inc.
  *

pkg/xl/management.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 /*
  * Minio Cloud Storage, (C) 2015 Minio, Inc.
  *

pkg/xl/multipart.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 /*
  * Minio Cloud Storage, (C) 2015 Minio, Inc.
  *

pkg/xl/node.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 /*
  * Minio Cloud Storage, (C) 2015 Minio, Inc.
  *

pkg/xl/xl-v1.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 /*
  * Minio Cloud Storage, (C) 2015 Minio, Inc.
  *

pkg/xl/xl-v1_test.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 /*
  * Minio Cloud Storage, (C) 2015 Minio, Inc.
  *

pkg/xl/xl-v2.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 /*
  * Minio Cloud Storage, (C) 2015 Minio, Inc.
  *

pkg/xl/xl-v2_test.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 /*
  * Minio Cloud Storage, (C) 2015 Minio, Inc.
  *