Allow django admin configuration

[meshy]

What was the problem:

• Setting up django's admin for Routes involved a lot of boilerplate.

How this solves the problem:

The basics have been rolled into this app.

There are still plenty of rough edges, and the documentation is woefully lacking, but it's been good to finally make some progress on this feature.

I'll get the docs and changelog in before pushing to get this merged.

Please ensure you have (if appropriate):

• [x] Run the test suite / style guide checkers.
• [x] Added tests.
• ~Updated the docs.~ deferred to #118.
• [x] Updated the changelog.

[meshy]

Tests not failing, but should, due to missing migrations. Test suite should be fixed in #117. Once that's done, I will rebase and continue.

Edit: done.

[meshy]

Going to merge as is. If you have any comments, please feel free to add them retroactively.