Bump src/cloud_controller_ng

Bump cloudfoundry/cloud_controller_ng:
  David Sabeti and Whitney Schaefer:
     Update api docs to reflect new service_binding_event metadata format ( Travis created: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/43785828 )
     Leave metadata empty for service_instance delete events ( Travis finished: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/43785507 )
     add user_provided_service_instance.* to valid types in api docs ( Travis started: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/43784689 )
     Record user_provided_service_instance event from serivce_instances_controller if the guid is for a user provided instance ( Travis Unknown )
     Fix typo ( Travis Unknown )
     Log error when event creation fails ( Travis Unknown )
  David Sabeti:
     Fix failing test for event repository spec ( Travis Success: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/43782266 )
     Failure to record service_dashboard_client_event no longer happens in the transaction ( Travis Failed: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/43780779 )
     Backfill tests for error handling in events_repository_spec ( Travis Unknown )
     Add assertions for space_id in service events ( Travis Unknown )
     Backfill test for record_service_purge_event ( Travis Unknown )
     Backfill test for record_service_binding_devent ( Travis Unknown )
     Move tests for user_provided_service_instance events to events_repository_spec ( Travis Unknown )
     Move tests for service instance events to events_repository_spec ( Travis Unknown )
     Move service_dashboard_client_events to event_repository_spec ( Travis Unknown )
     Move tests for service and service plan audit events to events_repository_spec ( Travis Unknown )
     Move edge case broker audit event tests to event_repository_spec ( Travis Unknown )
     Refactor some audit event specs ( Travis Unknown )