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 that could be the case, have you considered upgrading or do you plan to?

on a different note, +1 for [betterspecs.org](http://betterspecs.org/#contexts), we **really** need that for WSO, but its a massive task. Hopefully newer projects like OSRA can serve as a training ground for better specs :grinning: