Google site search

First pass at adding Google Site Search to the service manual.

Some caveats:
* it seems that some words will give no results at times (I was having trouble with "alpha", "beta" and "default").
* it doesn't update the URL so search results aren't bookmarkable
* using the main search box will update the URL, which will then be wrong for any successive searches
* it leaves two cookies, Google AJAX Search API and Google AdSense (despite AdSense being disabled in the admin). We should probably add a cookie warning somewhere.