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. 
Yaro, thank you for the suggestions.  The tests are cleaner as a result. (I was also able to remove a superfluous test).