Add OSRA Branches

PT Story: https://www.pivotaltracker.com/story/show/77972984

- [x] Added Branch model and seed data
- [x] Added Branch specs and factory
- [x] Added relationship between Sponsor and Branch
can these lines not be replaced with 
- bundle exec rake db:setup
should also speed up the build (original credit @NikitaAvvakumov)