To allow signing with addresses other than the commitment address, add
an alternate signature address. In order to continue to prove that the
address was chosen by the user, add an alternate signature history. Only
allow one record per ticket to be saved to cap needed db space.
**NOTE: This contains a backwards incompatible database migration, so if you plan to test it, please make a copy of your database first.**
Moves tickets from a single database bucket containing JSON encoded strings, to a bucket for each ticket.
This change is to preemptively deal with scaling issues seen with databases containing tens of thousands of tickets.
