Move all branching routes to Otter application.

75% of these were on OtterGroups anyways.
This will make tracing routes to apps easier.
Whitespace fix in groups route decorator.
Remove 'root' application and prefix routes.
Remove setting of resourse type on BaseApp.

This is handled in otter/rest/application.py for every app.
Remove BaseApp.

Explicit is better than implicit, and BaseApp did not provide anything
extra beside overhead.
Linting and Commenting.

Added docstring for all classes that had them missing or that were
incomplete.