IInputFormatter interface changes. 

1. Moving input formatting related classes to MVC Core.(for tests as well).
2. Cleaning up the IInputFormatter to the final version.
3. Updating the input formatters and the context to be compliant with the IInputFormatter interface.

- Not cleaning up TempInputFormatterProvider.
@rynowak , @dougbu - We didnt see a scenario which required anything but type. If you folks have one - will be happy to consider this.