Refactored SumoController, Made Controller helper methods Private

Made helper methods in the three main controllers (Sumo, Users, Stripe) Private. Also began refactoring the SumoController.

Signed-off-by: Daniel Long <wizazzle@gmail.com>
Finished Refactoring the SumoController

The next step will be to turn the message_action helper method in the SumoController into a a series of Commands, in order to prepare for the addition of the recurring billing feature.

Signed-off-by: Daniel Long <wizazzle@gmail.com>