VOL-595 - container image name consistency and general cleanup

Change-Id: Iccac1ccba61537cefa046118df139196e9e87713
diff --git a/compose/docker-compose-envoy-swarm.yml b/compose/docker-compose-envoy-swarm.yml
index b9e905d..fc299e9 100644
--- a/compose/docker-compose-envoy-swarm.yml
+++ b/compose/docker-compose-envoy-swarm.yml
@@ -10,7 +10,7 @@
 version: "3"
 services:
   voltha:
-    image: voltha/envoy:latest
+    image: "${REGISTRY}voltha/envoy:${TAG:-latest}"
     logging:
       driver: "json-file"
       options: