Publish events for tracking logs

This time, this is a single pull request, as my workflow wasn't as clean as usual.

Also, there is plenty of repetition, but I see no clean way to factor it out.
Just wanted to confirm the behavior of this event (in reference to https://github.com/edx-solutions/xblock-ooyala/pull/42#issuecomment-51632958)

How exactly does `OO.EVENTS.PLAYING` differ from `OO.EVENTS.PLAY`? We do need to capture the action of the video actually playing (i.e., when it's unpaused) -- is that what `OO.EVENTS.PLAYING` captures?