Upgrading server dependancies (#6431)

vendor/github.com/tylerb/graceful/README.md

@@ -3,6 +3,11 @@ graceful [![GoDoc](https://godoc.org/github.com/tylerb/graceful?status.png)](htt
 
 Graceful is a Go 1.3+ package enabling graceful shutdown of http.Handler servers.
 
+## Using Go 1.8?
+
+If you are using Go 1.8, you may not need to use this library! Consider using `http.Server`'s built-in [Shutdown()](https://golang.org/pkg/net/http/#Server.Shutdown)
+method for graceful shutdowns.
+
 ## Installation
 
 To install, simply execute: