Reintroducing AbstractController as BaseController, and adds in custom exceptions.
- Removed unused methods in NowplayingController that only threw exceptions
- Added an Exceptions namespace and UnsupportedMethodException which takes a method (HTTP verb) name
- Added in the currently supported verbs (GET, POST, PUT) as abstract methods and throws UnsupportedMethodException
Removed commented out JSON_PRETTY_PRINT constant from initial development