Add tracking for YouTube videos #2156

This is a WIP. I'm tracking the following events right now

1. Load event for YouTube videos
2. Play/Paused/Buffering/Finished status of the video
3. Video Quality
4. Errors, reported by YouTube API
5. 10% increments of video played.
Can we move this action value up to the 'action' property and drop the value altogether? It's easier to report on event actions than on event values.