ENHANCEMENT: Validate the tickets are still available before finishing the registration process.
ENHANCEMENT: Validate the tickets are still available before finishing the registration process.

stephenmcm/silverstripe-eventmanagement,souldigital/silverstripe-eventmanagement,registripe/registripe-core,silverstripe-australia/silverstripe-eventmanagement,souldigital/silverstripe-eventmanagement,burnbright/silverstripe-eventmanagement,burnbright/silverstripe-eventmanagement,stephenmcm/silverstripe-eventmanagement,silverstripe-australia/silverstripe-eventmanagement