VOL-595 - container image name consistency and general cleanup

Change-Id: Iccac1ccba61537cefa046118df139196e9e87713
diff --git a/compose/docker-compose-registry.yml b/compose/docker-compose-registry.yml
index dc6bb91..cb44be9 100644
--- a/compose/docker-compose-registry.yml
+++ b/compose/docker-compose-registry.yml
@@ -8,7 +8,7 @@
 version: "3"
 services:
   registry:
-    image: registry:2
+    image: "${REGISTRY}registry:${REGISTRY_TAG:-2}"
     logging:
       driver: "json-file"
       options: