gnome-settings-daemon string and UI changes

[Chris Coulson <chrisccoulson ubuntu com>]

Hi,

I've just made some changes to the low disk space warning in
gnome-settings-daemon. It now uses a dialog rather than libnotify. The
change also introduced some new strings.

The commit can be found here:
http://git.gnome.org/cgit/gnome-settings-daemon/commit/?id=8f1e770acb92682d1a5a4b7dd16049155cad2902

Regards
Chris