Migrate to dep (#3972)

* Update makefile to use dep

* Migrate to dep

* Fix some deps

* Try to find a better version for golang.org/x/net

* Try to find a better version for golang.org/x/oauth2

vendor/golang.org/x/text/language/gen_common.go

@@ -0,0 +1,20 @@
+// 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.
+
+// +build ignore
+
+package main
+
+// This file contains code common to the maketables.go and the package code.
+
+// langAliasType is the type of an alias in langAliasMap.
+type langAliasType int8
+
+const (
+	langDeprecated langAliasType = iota
+	langMacro
+	langLegacy
+
+	langAliasTypeUnknown langAliasType = -1
+)