Check in the vendor directory

Travis seems to be having issues pulling deps, so we'll have to check in
the vendor directory and prevent the makefile from trying to regenerate
it normally.

vendor/golang.org/x/net/http2/go19.go

@@ -0,0 +1,16 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build go1.9
+
+package http2
+
+import (
+	"net/http"
+)
+
+func configureServer19(s *http.Server, conf *Server) error {
+	s.RegisterOnShutdown(conf.state.startGracefulShutdown)
+	return nil
+}