Add support of several devise scopes

Commit adds:
- Possibility to use several devise scopes
- Add helper `authenticate_#{entity_underscored}_from_token` for each
  scope
- Add helper `authenticate_#{entity_underscored}_from_token!` for each
  scope
- Add helper `require_authentication_of_#{entity_underscored}!` for each
  scope
- Remove method authenticate_entity_from_token