Fix deprecation warning in the Django example

When I run the example I got the following warning. Making the prooposed change according to the django documentation will fix the issue

https://docs.djangoproject.com/en/dev/releases/1.4/#request-exceptions-are-now-always-logged

The warning 

/virtualenvs/allauth/lib/python2.7/site-packages/django/conf/__init__.py:221: DeprecationWarning: You have no filters defined on the 'mail_admins' logging handler: adding implicit debug-false-only filter. See http://docs.djangoproject.com/en/dev/releases/1.4/#request-exceptions-are-now-always-logged
  DeprecationWarning)
Merge pull request #431 from pmav99/patch-1

Fix deprecation warning in the Django example