Basic implementation of finish events
Add event object and addEventListener()
Add additional tests
Shave off some characters
Merge pull request #37 from alancutter/playerFinishEvent

Add Player onfinish events
support color and backgroundColor
Merge pull request #39 from tim-loh/color

support color and backgroundColor
Stop the rAF clock when there's no running animations.
Restart it when appropriate.
Review comments, ensure player tests work as expected.