title: Implement automatic version self-check and update in a PHP script with github
body: <p>Now that the code for <a href="http://github.com/xaccrocheur/nws" rel="nofollow">a small RSS-reading CMS</a> that I've done is hosted on github, I'd like it to </p>
  
  <ul>
  <li>check automatically if there is a newer version of itself's in the master branch</li>
  <li>Allow the user to update said script, ie it would overwrite itself with the newer version</li>
  </ul>