title: Django django-extensions commands unavailable ( graph_models )
body: <p>I'm trying to install django-extensions + graphviz + pygraph but i can't.
  I have done the following steps ( under Ubuntu ):</p>
  
  <pre><code>sudo apt-get install graphviz libgraphviz-dev graphviz-dev python-pygraphviz
  </code></pre>
  
  <p>in the project virtualenv (running python 2.7.2+):</p>
  
  <pre><code>source &lt;path to virtualenv&gt;/bin/activate
  pip install django django-extensions
  </code></pre>
  
  <p>if i run</p>
  
  <pre><code>which python
  </code></pre>
  
  <p>it selects the python in my virtualenv, so the python i'm using is the right one.
  in the virtualenv's site-package i have pygraphviz and django-extensions</p>
  
  <pre><code>python manage.py shell
  import django_extensions
  import pygraphviz 
  RUNS OK
  </code></pre>
  
  <p>in my django project i have added 'django_extensions' in my INSTALLED_APPS</p>
  
  <p>But when i run</p>
  
  <pre><code>python manage.py help
  </code></pre>
  
  <p>i can't see the commands and they are unavailable.</p>
  
  <pre><code>python manage.py graph_models -a -g -o model.png
  Unknown command: 'graph_models'
  Type 'manage.py help' for usage.
  </code></pre>
  
  <p>How can I fix this ?
  Thanks!</p>