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
This should call the validator with the action as provider, second param.

Validator has to take a provider it's not optional.

And mapper can just ask `omniauth_hash.is_a? OmniAuth::AuthHash`