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/ssh/testdata/doc.go

@@ -1,8 +0,0 @@
-// Copyright 2014 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.
-
-// This package contains test data shared between the various subpackages of
-// the golang.org/x/crypto/ssh package. Under no circumstance should
-// this data be used for production code.
-package testdata // import "golang.org/x/crypto/ssh/testdata"