refresh settings hover menu (bug 1103224)

- Separates the desktop settings gear from the navbar settings gear

![screen shot 2014-12-16 at 5 11 29 pm](https://cloud.githubusercontent.com/assets/674727/5465104/99dae26a-8546-11e4-86ef-29945645b296.png)

i like having a z-index grid containing semantically-named variables that define z-indexes from 1-10, rather than arbitrary numbers.