Add chosen library drop-down list

Chosen is a jquery plugin that allows for searching within a list.
This, of course, adds a jquery dependency.

[Here's their github page](http://harvesthq.github.com/chosen/)
Since the javascript libraries are linked with protocol-less urls, it won't render properly locally. [Here's a preview](http://hugo.grochau.com/firstworldproblems.biz/).