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/urfave/cli/appveyor.yml

@@ -1,24 +0,0 @@
-version: "{build}"
-
-os: Windows Server 2012 R2
-
-clone_folder: c:\gopath\src\github.com\urfave\cli
-
-environment:
-  GOPATH: C:\gopath
-  GOVERSION: 1.6
-  PYTHON: C:\Python27-x64
-  PYTHON_VERSION: 2.7.x
-  PYTHON_ARCH: 64
-
-install:
-- set PATH=%GOPATH%\bin;C:\go\bin;%PATH%
-- go version
-- go env
-- go get github.com/urfave/gfmrun/...
-- go get -v -t ./...
-
-build_script:
-- python runtests vet
-- python runtests test
-- python runtests gfmrun