changes searchbar collapse hamburger to use rotate plugin

This PR Fixes #23 . This changes the way that the searchbar collapse burger button looks and operates on click and uses the rotate jquery plugin. Though... might be unnecessary if/when we switch to font awesome.  

Ref #109 and #80 here

![screen shot 2014-05-16 at 3 02 14 pm](https://cloud.githubusercontent.com/assets/1656824/3002839/403b1b9c-dd46-11e3-92b0-4f4046853b21.png)


![screen shot 2014-05-16 at 3 02 17 pm](https://cloud.githubusercontent.com/assets/1656824/3002840/4354a1fe-dd46-11e3-966a-0f888271fde4.png)