Fix various issues around setting up a new dev instance of the site.

- Add registration to JINGO_EXCLUDE_APPS to prevent admin logout
  template from being rendered by Jinja.

- Update signal for default permissions to abort if the
  can_share_website permission doesn't exist yet, which occurs when
  creating an admin during the initial syncdb. Also adds tests for this
  signal.

- Update install docs to have correct paths.

- Remove FacebookDebugMiddleware; Facebook app testing can be done with
  a test app, and it causes import issues.

- Add Facebook app settings for tests.
Remove django-browserid submodule.
Install latest django-browserid.
Configure site for django-browserid, add placeholder login button.
Add dashboard, category list, and banner list views.
Clean up base/tests/__init__.py and tests relying on it a bit.
Add tests for banner views and landing/dashboard views.

Also tweak tests for 404 and 500 views to be more isolated.
Install django-braces.
Add image banner customization view and frontend.
Move to latest factory-boy.

Points the requirements file to the correct minimum version and updates
existing factories to point to new DjangoModelFactory class.

Also removes an extra factory from the Facebook tests.
Add tests for new models and banner creation process.

Also fixes issues with existing tests:
- Jenkins runs Python 2.6, which doesn't support using assert_raises as
  a context manager, so we use Django's version on TestCase, which uses
  the version from unittest2, which does support it.
- Set BannerFactory to be an abstract factory.