title: Close Gitlab issue via commit
body: <p>I spend my day doing this:</p>
  
  <ol>
  <li>Read an issue on a Gitlab-powered issue tracker,</li>
  <li>Fix the issue,</li>
  <li>Commit and push to the same Gitlab-powered Git server,</li>
  <li>Mark the issue as closed.</li>
  </ol>
  
  <p>To remove the 4th step, how can I close the issue automatically when committing?</p>