Implement general Fx Open Search for the site

* Upcoming Fx 33 has this on about:newtab... so best to get us in there early... does work with earlier versions too.
Drop off the .org portion to simplify the text a bit on what is shown

* Easily undone if needed but we, and just about everyone I've seen usually refer to ourselves as OUJS not OUJSO.

Applies to #254
Merge pull request #254 from Martii/openSearch

Implement general Fx Open Search for the site