title: Add custom task to Moodle cron job
body: <p>I'm working with Moodle 2.9, and trying to add some new task to cron. <br />
  Inside my <code>moodle/theme/portal</code> folder I added a <code>portal_cron()</code> function to <code>lib.php</code> file, then I run cron manually from command line but it's not working ?! 
  <br />
  Cron work normally but ignored my new task! <br />
  So what I'm doing wrong and how can I add new task to cron ?</p>