Add migration to create timecards

Timecards are a better representation of what we are after resftfully than start and stop signals.
Adds spec coverage for models
Updates model relationships with new objects
Adds frontend routes for timecards
Change end time to stop time
Updates functionality of timecard
Add timecop gem
Spec out timecard time functions
Use published scope to handle UI flow of timecard
Refactor timecard controller
Add errors output to timecards form
Migration to add relationship between activity id and timecard that led to it
Be more restful