updated ci to tag container with branch name instead of latest

.gitlab-ci.yml

@@ -9,12 +9,13 @@ stages:
 
 # Pack stage (docker build)
 pack:
+    variables:
+        IMAGE_TAG: ${CI_REGISTRY_IMAGE}:${CI_COMMIT_REF_NAME}
     stage: pack
     script:
         # Login to the registry. the variable is automatically set, build and push
         - TS=$(date +%Y%m%d%H%M)
         - docker login -u gitlab-ci-token -p $CI_BUILD_TOKEN $CI_REGISTRY
-        - docker build --no-cache -t $CI_REGISTRY_IMAGE:$TS .
-        - docker push $CI_REGISTRY_IMAGE:$TS
-        - docker tag $CI_REGISTRY_IMAGE:$TS $CI_REGISTRY_IMAGE:latest
-        - docker push $CI_REGISTRY_IMAGE:latest
+        - docker build --no-cache -t $IMAGE_TAG .
+        - docker push $IMAGE_TAG
+