Use CI_COMMIT_REF_SLUG instead CI_COMMIT_REF_NAME to get Docker image registry friendly names

Author: jordimas

.gitlab-ci.yml

@@ -33,13 +33,13 @@ build:
   stage: build
   script:
     - export REPO_NAME=$CI_REGISTRY_IMAGE/conjugador-elastic
-    - export IMAGE_NAME=$REPO_NAME:$CI_COMMIT_REF_NAME
+    - export IMAGE_NAME=$REPO_NAME:$CI_COMMIT_REF_SLUG
     - export DOCKER_PATH=docker/elasticsearch/Dockerfile
     - docker build -f $DOCKER_PATH --tag $IMAGE_NAME .
     - docker push $IMAGE_NAME
 
     - export REPO_NAME=$CI_REGISTRY_IMAGE/conjugador-webserver
-    - export IMAGE_NAME=$REPO_NAME:$CI_COMMIT_REF_NAME
+    - export IMAGE_NAME=$REPO_NAME:$CI_COMMIT_REF_SLUG
     - export DOCKER_PATH=docker/webserver/Dockerfile
     - docker build -f $DOCKER_PATH --tag $IMAGE_NAME .
     - docker push $IMAGE_NAME