Relationships

1) add view RelationshipsController specs
2) add Relationship model, specs
3) add validation on relationship to be unique
4) add user socializes spec - following, unfollowing

Please, approve.
Technically, this is a "already exists" context. Anytime you append "if ..." to a spec name, that is telling you that the spec belongs in said context and there is probably an opposite that need to be tested as well. I learned that at http://betterspecs.org/ which I highly recommend.