Remove the yellow outline from the search input

Currently, the search-box at http://plugins.jquery.com does not look very good in Chrome because of the yellow outline.

This tiny change removes it.

![plugins-jquery-com-yellow-outline-search-box](https://f.cloud.github.com/assets/67565/74501/6d3345dc-6094-11e2-8589-5e17f195ffe0.PNG)