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/github.com/stretchr/testify/LICENCE.txt

@@ -0,0 +1,22 @@
+Copyright (c) 2012 - 2013 Mat Ryer and Tyler Bunnell
+
+Please consider promoting this project if you find it useful.
+
+Permission is hereby granted, free of charge, to any person 
+obtaining a copy of this software and associated documentation 
+files (the "Software"), to deal in the Software without restriction, 
+including without limitation the rights to use, copy, modify, merge, 
+publish, distribute, sublicense, and/or sell copies of the Software, 
+and to permit persons to whom the Software is furnished to do so, 
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included
+in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES 
+OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 
+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 
+DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT 
+OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE 
+OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

vendor/github.com/stretchr/testify/assert/assertion_format.go.tmpl

@@ -1,4 +0,0 @@
-{{.CommentFormat}}
-func {{.DocInfo.Name}}f(t TestingT, {{.ParamsFormat}}) bool {
-	return {{.DocInfo.Name}}(t, {{.ForwardedParamsFormat}})
-}

vendor/github.com/stretchr/testify/assert/assertion_forward.go.tmpl

@@ -1,4 +0,0 @@
-{{.CommentWithoutT "a"}}
-func (a *Assertions) {{.DocInfo.Name}}({{.Params}}) bool {
-	return {{.DocInfo.Name}}(a.t, {{.ForwardedParams}})
-}