Merge branch '370-fix-runner-caching-issue' into 'master'

Fix runner caching issue and add suffix to cache name

Closes #370

See merge request !656

.gitlab-ci.yml

@@ -21,7 +21,7 @@ stages:
         prefix: "$CI_JOB_IMAGE"
       paths:
         - vendor/bundle
-    - key: jumbotron-cache
+    - key: jumbotron-cache-$CI_COMMIT_REF_SLUG
       paths:
         - assets/img/jumbotrons/desktop
         - assets/img/jumbotrons/display_2k