title: Project/Task tracking tool with notifications
body: <p>I am looking for a particular project/task tracking tool with :</p>
  
  <ol>
  <li>Ability to define hierarchy of task. Like Project -> Task -> Sub-task etc.</li>
  <li>Ability to assign owner.</li>
  <li>Status level like NotStarted, Inprogress, Impeded, Complete</li>
  <li>Notification based i.e. any change should be notified through an email or RSS feed.</li>
  <li>Open source</li>
  </ol>
  
  <p>Thanks.</p>