Deprecate Jekyll site, merge into Django templates

This deprecates what **used** to be `foia-hub` (and is now [`foia-design`](https://github.com/18F/foia-design))  and moves our [prototype](https://github.com/18F/foia-design/pull/40 into Django-land.

I've rearranged the includes (since proper dynamic insertion of template blocks mean we can structure them differently than Jekyll), changed `/assets/` to `/static/`, set the `STATICFILES_DIR` to `/foia-hub/static`, and reproduced the routes.

Some next areas of fixing/improvement:

* cache-busting URLs, couldn't figure out jinja2's datetime equivalence stuff
* I am not looking up the agency/office by slug yet, it is depending on dynamic partial templates being in-place, which is not a good idea
* marking which tab at the top of the screen is "current"
* agency data is still statically committed to the repo, but should be fetched by API call (this could have been done even when we were on Jekyll, but it is even more obvious now)

I commented out some code that was stopping the contact loading script from running, it expected a `folder` variable to be defined when it wasn't. I think that was some semi-committed code. As this stabilizes, we should start getting some functional tests in place (though testing out worker ETL scripts will mean getting into annoying unit-level tests, which are brittle).