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.
@NikitaAvvakumov oh, rewrite that line to: `let(:attributes) { { sponsor_type_code: '' } }`, its a little weird but the block must contain a valid hash (I make this mistake myself many times)