Add Stylish formatter and make it default. Fixes #517

> Add Stylish formatter and make it default. Fixes #517

https://github.com/sindresorhus/eslint-stylish

![screen shot 2014-01-16 at 23 59 12](https://f.cloud.github.com/assets/170270/1936009/26483596-7f02-11e3-9046-04fa938a79a1.png)