Overflow-hidden for sidenav lis

If a property name is too long it gets out of the li box, so text is seen over the right block with content

![screen shot 2013-12-18 at 11 15 16 pm](https://f.cloud.github.com/assets/1782569/1776705/3abc4296-681a-11e3-8894-c2b61d0e9131.png)