crosswalk extension

This is a fully working modification enabling the use of Cloudeebus inside Crosswalk without going through WebSocket.

This depends on some unmerged changes in Crosswalk (https://github.com/crosswalk-project/crosswalk/pull/2121#issuecomment-47094707) and pycrosswalk (https://github.com/tmpsantos/pycrosswalk/commit/5ccd1958b61b39e3a789cb2bf3264defac85905d#commitcomment-6819102).

So at this time, please only review and do not merge yet.