Update csscomb.js to version 2.0

- Update csscomb.js to version 2.0.x
- Use `.csscomb.json` as config file if it's present
- Use `comb.getConfig()` to get default config
- Rename `sortOrder` option to `config`

Fixes #11.

![tumblr_mvf3s0dmtm1rikt3no1_400](https://f.cloud.github.com/assets/872004/1776934/5fe17b56-681d-11e3-9264-4cbb1dbce1ee.gif)