Move Chrome extension on new API

* Remove deprecated functions in Chrome extension
* Fix task **concat** in Rakefile

Link on task in Chromium task tracker:
[Issue 296207](https://code.google.com/p/chromium/issues/detail?id=296207&q=livereload&colspec=ID%20Pri%20M%20Iteration%20ReleaseBlock%20Cr%20Status%20Owner%20Summary%20OS%20Modified)