add back master only for ruby 2.1 images

.gitlab-ci.yml

@@ -145,9 +145,8 @@ spec:ruby21:
   tags:
     - ruby
     - mysql
-# TODO: put this back after testing
-#  only:
-#  - master
+  only:
+  - master
 spinach:ruby21:
   image: ruby:2.1
@@ -156,6 +155,5 @@ spinach:ruby21:
   tags:
     - ruby
     - mysql
-# TODO: put this back after testing
-#  only:
-#  - master
+  only:
+  - master