Allow manualRotation to be overridden

[cvan]

If it's useful, perhaps manualRotation should be able to be overridden via querystring/hash/postMessage à la the video URL, autoplay, etc. settings.

And if this project offers a bundle (#21) exposed as a global (or a requirable module), then manualRotation could be one of the options passed in when the player is constructed and/or later when a video is played.