css

This adds CSS live document support on top of sebaslv's PR#3.
What do this do? Does it change the ending condition of the cycle (`i < document.styleSheets.length`)?

Why not take [this implementation](https://github.com/busykai/brackets-livedev2/pull/10#issuecomment-46570902) instead which create `script` node for each `link` only once?