Add auto-acceptance for registrations

[dunkOnIT]

• [ ] Create a decision tree of when a registration can be auto-accepted
  • [ ] What's the basic 'success case'
• [ ] Concurrency issues:
  • [ ] Between different registration
  • [ ] Between the same registration
  • [ ] Do we start payment before confirming the previous status change?
• [ ] How is one step aware of the preceeding steps and able to confirm that they've occurred, without needing to query the queue? (dependency between steps)