cleanup: rename package and vendor dependencies for old go versions

Fixes #8 and begins to address deployability.

vendor/golang.org/x/net/http2/not_go111.go

@@ -0,0 +1,20 @@
+// Copyright 2018 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 !go1.11
+
+package http2
+
+import (
+	"net/http/httptrace"
+	"net/textproto"
+)
+
+func traceHasWroteHeaderField(trace *httptrace.ClientTrace) bool { return false }
+
+func traceWroteHeaderField(trace *httptrace.ClientTrace, k, v string) {}
+
+func traceGot1xxResponseFunc(trace *httptrace.ClientTrace) func(int, textproto.MIMEHeader) error {
+	return nil
+}