Refactor the auth/enroll requests into separate services

Plus:
- Clean-up some old stuff.
- Use dagger for dependency injection.

NOTE: Although the auth and roll requests are now moved outside the activities
there is still some stuff in the services themselves that need some refactoring
in the future.
wrap in if debug, or create your own logger like this one: https://github.com/spaarspot/spaarspot-android/blob/master/Application/src/main/java/nl/spaarspot/data/utils/Log.java