Replace godep with dep

vendor/golang.org/x/crypto/README.md

@@ -0,0 +1,21 @@
+# Go Cryptography
+
+This repository holds supplementary Go cryptography libraries.
+
+## Download/Install
+
+The easiest way to install is to run `go get -u golang.org/x/crypto/...`. You
+can also manually git clone the repository to `$GOPATH/src/golang.org/x/crypto`.
+
+## Report Issues / Send Patches
+
+This repository uses Gerrit for code changes. To learn how to submit changes to
+this repository, see https://golang.org/doc/contribute.html.
+
+The main issue tracker for the crypto repository is located at
+https://github.com/golang/go/issues. Prefix your issue with "x/crypto:" in the
+subject line, so it is easy to find.
+
+Note that contributions to the cryptography package receive additional scrutiny
+due to their sensitive nature. Patches may take longer than normal to receive
+feedback.