Added API Views for questions.

If you make a Category and a Question and an Opinion then the following
below will give you some happy happy Data. Need to write tests for this
stuff soon though, but working through the REST framework they haven't
gotten to testing yet.

http://127.0.0.1:8000/questions/categories/
http://127.0.0.1:8000/questions/category/1/
http://127.0.0.1:8000/questions/1/opinions/
Added Admin Interface for Questions list.

Added vote aggregation functions (django has a weird group by syntax)

Added Question model and Category model to the admin dashboard, not
adding opinions because we don't mess with those.

Rewrote a couple tests and added some more.

Named the URL's for use in test/views.