Analytics plugin first pass

OK, I think this is ready to merge for-realz.

Analytics plugin for ubersystem, should be able to drop in for both AC and Magfest no problem.

This is also the first real UI-heavy, database-heavy plugin to be used and those functionalities all seem to work well, which is awesome.

This displays graphs of paying attendance. Excludes: paying dealers, comp'd staff/vip/guest/etc badges, refunded badges.  We want to know how many badges were purchased by the actual general public.

Off the shelf, this plugin displays only the live registration data on a graph (which, is the main point and is super-useful).

However, if you have historical data, you simply drop a json file with the old data in a particular dir in your deploy, and it will merge that with the live data.

There's a few hacky things here (i.e. ANYTHING to do with UI design, responsive, making it look pretty, CSS, etc because I have no patience for that).

@EliAndrewC I'd appreciate a good hard look at my __init__.py to make sure I'm not doing anything too dumb in there with mounting the app config/etc.
You should definitely make a copy of ESCHATON before you make any modifications to it.  ``DATES['ESCHATON']`` is globally shared, so when you use ``.replace()`` you're actually mutating its value, which seems bad.

You should instead say something like ``eschaton = deepcopy(ESCHATON)`` to make a copy before doing any modifications.