title: How can I debug plugins that are being silently ignored?
body: <p>Newcomer to Jekyll here (previously on Hyde). </p>
  
  <ul>
  <li>Ruby files placed in the _plugins/ directory are apparently silently ignored. </li>
  <li>I am using version 0.11.2 of Jekyll, with ruby 1.8.7 on Ubuntu 12.04.</li>
  </ul>
  
  <p>Should an extra config parameter be added to load these plugins? The doc doesn't say so - the sane default should be to look into _plugins, and they should be required automatically. How can one debug the loading of Jekyll plugins?</p>