Support csscomb.js (close #5)

This grunt plugin now uses [csscomb.js](http://github.com/csscomb/csscomb.js) instead of [php version of csscomb](http://github.com/csscomb/csscomb):
Tests are updated.

Note that version is changed to 1.0.0.

![funny-cat-aerobics-on-exercise-balls](https://f.cloud.github.com/assets/872004/1504814/934b03f8-48c5-11e3-9093-d932cab702e4.gif)