De-AASHE-fying.

Removed dependency on aashe-auth.

Split requirements.txt, bulletin/urls.py and bulletin/settings.py
into two pieces, each.

Requirements of django-bulletin are in default_requirements.txt. This is
included in requirements.txt. Use requirements.txt for any additional
requirements your project has.

There's bulletin/default_urls.py, which includes the URLs
django-bulletin requires. It's included in bulletin/urls.py, which is
where you should add any URLs you need.

Finally, bulletin/default_settings.py includes settings you can override
or add to in bulletin/settings.py.
Was missing a couple imports.
Rm'ed aashe-auth URLs from base template.