Error Styles

- make errors look decent
- move error styles to their own stylesheet
- create errors partial

Screenshot shows `ul.errors` and a `p.error` below it.

![screen shot 2014-11-13 at 2 39 21 pm](https://cloud.githubusercontent.com/assets/2289/5038352/540242fe-6b44-11e4-956a-340e7f3abccc.png)