vendor: update all dependencies except Azure SDK

The Azure SDK doesn't support Go 1.5 anymore. We can't upgrade it until
Go 1.8 comes out.

vendor/golang.org/x/net/websocket/websocket.go

@@ -4,6 +4,12 @@
 
 // Package websocket implements a client and server for the WebSocket protocol
 // as specified in RFC 6455.
+//
+// This package currently lacks some features found in an alternative
+// and more actively maintained WebSocket package:
+//
+//     https://godoc.org/github.com/gorilla/websocket
+//
 package websocket // import "golang.org/x/net/websocket"
 
 import (