Add missing submit button in add application page.
Add link in the homepage to view published ``Applications``.
Add mechanics to diferentiate an idea from an app.

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

The ``Application`` can be at two different stages:

- Idea.
- Application.

Once the ``IDEA`` is complete it can become an ``APPLICATION``.

The ``stage`` is determined by an ``IntegerField`` in the
``Application`` model.

Closes #31.