Support of React JSX

Support of React JavaScript XML.
React JSX: http://facebook.github.io/react/docs/jsx-in-depth.html

NOTE:
Please, find "Green" bild on https://github.com/ademin/tilt to be sure that current changes don't break anything.
The master branch contains 2 aditional commits that fixes build issues. 
One of them is waiting to be approved: https://github.com/rtomayko/tilt/pull/216
Another one requires Bluecloth support to be removed from tilt, since it has been using 'discount' library as well as RDiscount gem done. Bluecloth haven't been updated for a long time!!! There are conficts between them. Anyway, it doesn't relate to React JSX.