title: Gitlab job when tagging a release
body: <p>So I have a Gitlab 8.1 instance running. Everything (nearly) is working as intended. I have deployment and build jobs that execute when I merge to different branches. </p>
  
  <p>But I'd like to create a tarball every time I tag a new version of my project. But I can't seem to figure out the conditions required to trigger that sort of job. </p>
  
  <p>I tag releases in version names (ie. v0.9.1-beta). And I have this in my .gitlab-ci.yml for the project: </p>
  
  <pre><code>build_release:
    script:
      - composer update
      - cd ..
      - tar cvzf $CI_BUILD_REF_NAME.tar.gz kin
  stage: build
  except:
    - production
    - develop
    - ^enhancement\/.*$
    - ^feature\/.*$
    - ^bugfix\/.*$
  </code></pre>
  
  <p>But it doesn't trigger. Please help. </p>