Implement factory girl

Pivotal Tracker story Switch to FactoryGirl: https://www.pivotaltracker.com/story/show/75757844.
- add factory_girl_rails gem
- create factories for partners, provinces, sponsor_types, sponsors, statuses
- create model spec for sponsor_type using sponsor_types factory

All factories confirmed to create valid objects.
Currently, the test breaks. It is extremely unlikely that the factory will get called enough times for this to happen, but I share your reservations. While the names are not validated at present, the codes are: they have to be unique and also belong to the set you see above, so they are a finite resource.
We are discussing alternative implementations of this, such as seeding the test db with existing names and codes and using those instead of a factory.

There are also questions about how to implement provinces in dev/production. We have discussed making the db read-only or disabling edit & delete functionalities. We will probably have to remove code validation to allow future additions.