hookup_manager stage one:  New tables for pending and active hookups (pair programming events).  Pivotal #75025008, 75025492

New tables for pending and active hookups (pair programming events).
Pivotal stories:
 "display list of pending events in a table", https://www.pivotaltracker.com/s/projects/982890/stories/75025008, and 
"display list of active/live hookups (i.e. hookups with live hangouts) in a separate table",https://www.pivotaltracker.com/s/projects/982890/stories/75025492. 
Added a hookups view, a hookups controller with an index service, and several methods to the events model to distinguish pending, active, and expired events.
I'm working on the assumption, for now at least, that all hookups will be single events, i.e. non-repeating.  And since I'm only displaying hookups, I'm not testing for repeating events.  I'll probably need to refactor the tests more as I refactor the active?, pending?, expired? methods.