Use Frack for ticket queries/events

I think that for the transitional period where Trac is still running, Trac will need to be modified to send notifications to Frack.

Alternately, we could modify the postgres schema as described in http://stackoverflow.com/questions/5412474/using-pg-notify-in-postgresql-trigger-function and then use LISTEN from frack, so that we don't have to touch trac's code. But Frack still has to find out about changes that it didn't make itself.

kenaan could also monitor both for events (and deduplicate). There's going to be a hack _somewhere_, but keeping it in kenaan might be best (kenaan needs to add support for frack first anyway, so we can just not delete the trac support until we stop running trac).