VOL-595 - container image name consistency and general cleanup

Change-Id: Iccac1ccba61537cefa046118df139196e9e87713
diff --git a/docker/Dockerfile.tester b/docker/Dockerfile.tester
index 617ef13..a9b1a10 100644
--- a/docker/Dockerfile.tester
+++ b/docker/Dockerfile.tester
@@ -1,4 +1,20 @@
-FROM cord/voltha-base
+# Copyright 2018 the original author or authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+ARG TAG=latest
+
+FROM voltha/voltha-base:${TAG}
 
 MAINTAINER Zsolt Haraszti <zharaszt@ciena.com>
 MAINTAINER Ali Al-Shabibi <ali.al-shabibi@onlab.us>