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.
@yggie I've been with OSRA for 2 days so it's not my call to make. 

My opinion, though, is that now would be the time do it as there are only 38 tests total. The project's complexity is increasing though, plus the coverage for the existing code ought to be improved, so upgrading later may be more painful.

@motasem-salem, @PurityControl what do you think? I'd be happy to do the upgrade and refactor the existing specs as needed.