Gnote Search Provider for Gnome Shell

[Casey Harkins <caseyharkins gmail com>]

NOTE: I tried to send this to this list a few days ago, but it doesn't
appear to have gone through. 

I threw together a quick proof of concept gnote search provider for
gnome shell. It requires the asynchronous search providers patch from
gnome bug #655220:

https://bugzilla.gnome.org/show_bug.cgi?id=655220

Apply the patch then grab the extension from:

http://tuxfoo.org/gnome-shell-gnotesearch.tar.bz2

Extract it to:
~/.local/share/gnome-shell/extensions.

Its ugly, but functional. If the async patch gets applied upstream, I
might improve this (unless someone else beats me to it). There are
almost certainly potential race conditions / concurrency issues with
this implementation (see this._results and this._expected), though it
wouldn't be too much effort to straighten those out using a search
result object where each instance has its own result array and
callbacks for receiving the results from gnote.

-casey