Add functionality to submit apps

https://github.com/madewithbytes/us_ignite/issues/31

Authenticated users can submit an ``Application``,
the application is a ``draft`` by default, the only
required fields are ``name`` and ``description``.

The ``REMOVED`` status will be only used by
the administrators of the site.

Refers: #31, #32, #30, #29, #24.

Closes: #19.