hookup_tables

relates to pivotal stories "display list of pending events in a table", 75025008, and "display list of active/live hookups (i.e. hookups with live hangouts) in a separate table",75025492. 
Oops... I must be overtired.  I was thinking about a different line..
  validate :from_must_come_before_to

That should be a separate PR since it fixes a bug.