VOL-595 - container image name consistency and general cleanup

Change-Id: Iccac1ccba61537cefa046118df139196e9e87713
diff --git a/compose/docker-compose-logstash.yml b/compose/docker-compose-logstash.yml
index 38a5881..53a875f 100644
--- a/compose/docker-compose-logstash.yml
+++ b/compose/docker-compose-logstash.yml
@@ -2,7 +2,7 @@
 
 services:
   logstash:
-    image: cord/logstash
+    image: "${REGISTRY}voltha/logstash:${TAG:-latest}"
     environment:
       - log.level=info
     command: logstash -f /etc/logstash/conf.d/