Vid 165 youtube tracking

This pull request adds video player tracking to youtube videos with the iframe js api.  Since this is the second provider that I'm adding this type of tracking to, I've abstracted a bunch of things so they can be used by both providers (ooyala and youtube).  

This is all going in to the bugid-98408 branch which includes an overall refactor of VideoHandlers to be more service oriented so it can work for both mobile and desktop. We hope to release this branch to production on 5/15. 

@hakubo, @saipetch, @garthwebb, @kflorence maybe one or two of you can do a code review.  Thanks!