Fix app_settings import

The url paths:
```
    url(r'^rest-auth/', include('rest_auth.urls')),
    url(r'^rest-auth/registration/', include('rest_auth.registration.urls')),
```
Weren't working for me, I kept getting an ImportError `No module named 'app_settings'`.
This fixes that issue for me on Win7 x64, Python 3.4, Django 1.7