Add stages to the context.

https://github.com/madewithbytes/us_ignite/issues/251
Add sub menu to the ``applications``.

https://github.com/madewithbytes/us_ignite/issues/251
Update ``language_code`` to en-us.
Add middlware to redirect valid HOST requests.

The middleware will redirect accepted HTTP_HOSTS
to the specified SITE_URL.
Enable redirect middleware in all the environments.
Disable redirect middleware during testing.
Added herokuapp domain to the allowed HOSTS.
Add ``StaticPage`` to describe static pages.
Add admin section to the ``StaticPage``.
Add visibility mechanics to the ``SectionPage`` model.
Add view for ``SectionPage`` detail.

The ``SectionPage`` detail appears in the ``about``
``get-detail``.
Add detail page for the section pages.
Configure admin to receive HTML.
Add raven sentry client.
Update fabric load db command.
Update ``taggit`` dependency.
Bugfix: Missing class on bottom list.
Update markup slugs for domains.

https://github.com/madewithbytes/us_ignite/issues/239
Add domain icon to the application title.
Add help text to upload images.