Search UI adjustments

:fork_and_knife: This changes a few minor UI items when searching for cookbooks.

- Change filter by to sort by
- Remove created at date from cookbook search results
- Allow users to unselect a search filter by clicking on the filter again
- Change search title to number of cookbooks returned
- Use longish time format for updated at date for cookbook search results

![screen shot 2014-05-05 at 4 46 19 pm](https://cloud.githubusercontent.com/assets/316507/2883061/60ba9270-d496-11e3-9fc4-1087f528c5c8.png)