Refactored StripeController (Extracted 2 Classes)

Extracted the StripeEvent class and the ExceptionLogger class from the StripeController. Currently, changes have been applied only to the StripeTestController, leaving the StripeController the same as the previous commit for now. Check the StripeTestController for current changes to that file.

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