hookup_manager stage one:  New tables for pending and active hookups (pair programming events)

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. 
I think that I have a good fix now, in commit dda9e00
 (I forgot to change the comment when committing it...)
Rather than stubbing active?, I am creating a hangout with a hangout_url for each event, and set the Time.now and the event times so that the events appear to be active. These are the conditions to make active? true.