[Answer]-No module named auth.urls

social_auth Application Setup:

INSTALLED_APPS = (
    ...
    'social_auth'
)

Ok I figured out your problem, you are using like social.auth.urls but you should use social_auth.urls

In urls.py:

urlpatterns = patterns('',
    ...
    url(r'', include('social_auth.urls')),
    ...
)

Link http://django-social-auth.readthedocs.org/en/latest/configuration.html