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/Makefile b/demo_test/Makefile
index 0e206de..3bbfb73 100644
--- a/demo_test/Makefile
+++ b/demo_test/Makefile
@@ -40,8 +40,8 @@
 	go get github.com/sirupsen/logrus
 	go get github.com/Shopify/sarama
 
-demotest: prereq proto/importer.pb.go
-	go build -i -v -o $@
+demotest: proto/importer.pb.go
+	GO111MODULE=on go build -mod=vendor -i -v -o $@
 
 proto/importer.pb.go: ../proto/importer.proto
 	mkdir -p proto