Update Player to new timing model and API
Add tests for new player API
Update existing tests to new player API
Update existing test to new player timing behaviour (currentTime does not progress beyond end)
Update test-player-cleanup.html to match new player timing behaviour
Merge remote-tracking branch 'origin/master' into newPlayerAPI

Conflicts:
	web-animations.js
Merge pull request #543 from alancutter/newPlayerAPI

Update Player timing model and API to match spec