Feature/omniauthhelper rehash

- Fixed #20 by rewriting OmniAuthHashHelper and OmniAuthHelper into `lib/login/omni_auth_hash_manager/validator.rb` and `mapper.rb`
- Full coverage for this new strategy
- Rewrote old tests to work in new strategy
These are actually 3 features which 2 scenarios a piece: 1 for logged in, 1 for logged out.