SEBA-902 single-olt tests;
Pin protoc-gen-go to 1.3.2 to resolve compatibility issue;
Run go mod tidy / go mod vendor on importer;
Add Go Module support to demotest

Change-Id: Ifde824fc9a6317b0adc1e12bea54ee1f9b788906
diff --git a/demo_test/vendor/golang.org/x/net/http2/not_go111.go b/demo_test/vendor/golang.org/x/net/http2/not_go111.go
new file mode 100644
index 0000000..161bca7
--- /dev/null
+++ b/demo_test/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
+}