Reviewed Authorization input filter

- CS fixes
- Test normalization
- Refactor to extend InputFilter (simpler implementation)
Reviewed ContentNegotiation input filter

- Refactored to extend InputFilter instead of implement
  InputFilterInterface.
- Updated to both check for `class_exists` as well as
  `class_implements`.
- Updated to have flat array of messages.
- Normalized unit tests and added additional cases.