Initial delivery of metrics code (#81)

* Initial delivery of metrics code

* Fix build issues

* Fix build issue with go vet

vendor/golang.org/x/crypto/blake2b/blake2b_amd64.go

@@ -1,25 +0,0 @@
-// Copyright 2016 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build !go1.7,amd64,!gccgo,!appengine
-
-package blake2b
-
-func init() {
-	useSSE4 = supportsSSE4()
-}
-
-//go:noescape
-func supportsSSE4() bool
-
-//go:noescape
-func hashBlocksSSE4(h *[8]uint64, c *[2]uint64, flag uint64, blocks []byte)
-
-func hashBlocks(h *[8]uint64, c *[2]uint64, flag uint64, blocks []byte) {
-	if useSSE4 {
-		hashBlocksSSE4(h, c, flag, blocks)
-	} else {
-		hashBlocksGeneric(h, c, flag, blocks)
-	}
-}