Update use of DOCKER_OW_IMAGE_PREFIX (#195)

diff --git a/docker-compose/docker-compose.packages.yml b/docker-compose/docker-compose.packages.yml
index 0e4a62b..c91e98c 100644
--- a/docker-compose/docker-compose.packages.yml
+++ b/docker-compose/docker-compose.packages.yml
@@ -1,7 +1,7 @@
 version: '3'
 services:
   alarmsprovider:
-    image: ${DOCKER_OW_IMAGE_PREFIX:-openwhisk}/alarmprovider
+    image: ${DOCKER_IMAGE_PREFIX:-openwhisk}/alarmprovider
     ports:
       - "8081:8080"
     links:
@@ -21,7 +21,7 @@
     volumes:
       - ~/tmp/openwhisk/alarmsprovider:/logs
   cloudantprovider:
-    image: ${DOCKER_OW_IMAGE_PREFIX:-openwhisk}/cloudantprovider
+    image: ${DOCKER_IMAGE_PREFIX:-openwhisk}/cloudantprovider
     ports:
       - "8082:8080"
     links:
@@ -41,7 +41,7 @@
     volumes:
       - ~/tmp/openwhisk/cloudantprovider:/logs
   kafkaprovider:
-    image: ${DOCKER_OW_IMAGE_PREFIX:-openwhisk}/kafkaprovider
+    image: ${DOCKER_IMAGE_PREFIX:-openwhisk}/kafkaprovider
     command: /bin/bash -c "cd KafkaFeedProvider && python -u app.py >> /logs/kafkaTrigger_logs.log 2>&1"
     ports:
       - "5000:5000"
diff --git a/docker-compose/docker-compose.yml b/docker-compose/docker-compose.yml
index b33226f..3060f2f 100644
--- a/docker-compose/docker-compose.yml
+++ b/docker-compose/docker-compose.yml
@@ -37,7 +37,7 @@
 
   # WHISK CONTROLLER
   controller:
-    image: ${DOCKER_OW_IMAGE_PREFIX:-openwhisk}/controller
+    image: ${DOCKER_IMAGE_PREFIX:-openwhisk}/controller
     command: /bin/sh -c "exec /init.sh 0 >> /home/owuser/controller-local_logs.log 2>&1"
     links:
       - db:db.docker
@@ -79,7 +79,7 @@
 
   # WHISK INVOKER AGENT
   invoker:
-    image: ${DOCKER_OW_IMAGE_PREFIX:-openwhisk}/invoker
+    image: ${DOCKER_IMAGE_PREFIX:-openwhisk}/invoker
     command: /bin/sh -c "exec /init.sh --id 0 >> /logs/invoker-local_logs.log 2>&1"
     privileged: true
     pid: "host"