style(lists): Add new 'list' and 'item' classes for easy list styles

BREAKING CHANGE: This removes the default 'ol' styles for modal forms.
To keep the decimal list look, add a 'list' class to the `<ol>`

![lists](https://cloud.githubusercontent.com/assets/706039/3403645/5a727c8e-fd68-11e3-88ad-63852fc8b615.gif)

(I might be having too much fun making gifs, but why not?)