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.
many of these tests can be done in a much more concise manner using the amazing matchers from thoughtbot's [shoulda-matchers](https://github.com/thoughtbot/shoulda-matchers) gem. For example:

~~~ruby
it { is_expected.to validate_presence_of(:name) }
it { is_expected.to validate_presence_of(:code) }
it { is_expected.to validate_uniqueness_of(:name) }
~~~