Instead of charging the customer using the attached payment
method and then creating the invoice, we create an invoice and
force an immediate payment for the invoice via the attached
payment method.
This commit refactors 'event_status' view and adds
'BillingSession.get_event_status' method.
This refactoring will help in minimizing duplicate code
while supporting both realm and remote_server customers.
Adds request as a parameter to json_success as a refactor towards
making `ignored_parameters_unsupported` functionality available
for all API endpoints.
Also, removes any data parameters that are an empty dict or
a dict with the generic success response values.