The DOM tree of YouTube page is changed.
A new element with the id of "player-mole-container" is added.
It's necessary to seperate the YOUTUBE_PLAYER_CONTAINER from the
YOUTUBE_WATCH to manage this change.
Otherwise, the class like "watch-small", "watch-medium" can't be set to
the target correctly, which will cause a player-resizing bug.
Always check the "embiggen" option.
Merge pull request #48 from tyeen/master

The DOM tree of YouTube page is changed.