Added PhysicalTicket model and controller. It holds the information about each physical ticket bought at the purchase. Physical Tickets are created after every successfull payment.
If the registration period is over then speakers of confirmed events
can't register anymore. They should be able to, since they are gonna be
there anyway.
* Allow the speakers of confirmed events to register regardless of the
registration period
* Provision for registrations of confirmed speakers, so as not to
exceed the registration limit
* Add scope for registered speakers
Fix#829 and fix#802
