*adds 'timer-end' event and $scope.end function

*adds 'timer-end' event and $scope.end() function
*adds 'timer-resumed' and 'timer-started' events
*BREAKING CHANGE: changes the function called after end of countdown from $scope.stop() to $scope.end()

There is a general semantic issue with the 'end' and 'ended' events. They are there to signify both 'pause' and 'end'. This means that the timer is also not properly restarted (or restartable). I assume this comes from the fact that countdown functionality was added later, and that's when the pause/end distinciton is important.

The problem is that simply removing stop() is a hugely breaking change. So I chose to leave it as-is as a 'synonym' for 'pause', and introduced 'end' as a new event. However this means I must make the lesser breaking change of reconfiguring which event gets triggerred on the end of the countdown. This isn't as much of a problem as the use of $scope.stop() was kind of problematic anyway. There was no way to restart the countdown, so you could only really do a countdown once.

Hopefully this change makes sense, let me know if not.