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/vendor/google.golang.org/grpc/go.mod b/vendor/google.golang.org/grpc/go.mod
index 2378361..84c98c2 100644
--- a/vendor/google.golang.org/grpc/go.mod
+++ b/vendor/google.golang.org/grpc/go.mod
@@ -3,11 +3,11 @@
 go 1.11
 
 require (
-	github.com/envoyproxy/go-control-plane v0.9.1-0.20191026205805-5f8ba28d4473
+	github.com/envoyproxy/go-control-plane v0.9.4
 	github.com/envoyproxy/protoc-gen-validate v0.1.0
 	github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b
 	github.com/golang/mock v1.1.1
-	github.com/golang/protobuf v1.3.2
+	github.com/golang/protobuf v1.3.3
 	github.com/google/go-cmp v0.2.0
 	golang.org/x/net v0.0.0-20190311183353-d8887717615a
 	golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be