Changed in Django 1.5: cleanup is deprecated. Use clearsessions instead.

Currently django-extensions shows the following warning when running `python -W default manage.py runjobs daily`:

> /path/to/virtual/local/lib/python2.7/site-packages/django/core/management/commands/cleanup.py:10: PendingDeprecationWarning: The `cleanup` command has been deprecated in favor of `clearsessions`.
  PendingDeprecationWarning)

This was [changed in Django 1.5](https://docs.djangoproject.com/en/1.5/ref/django-admin/#cleanup)