[Desktop13.04-Topic] Drop gconf from the default installation

[Sebastien Bacher]

Hey again,

It seems we could finally get ride of libgconf2-4 users next cycle, 
looking on current quantal we still some users, including:

- gksu (can be replaced by pkexec)
- gnome-media (through libgnome-media-profile, we probably need to port 
that one)
- lightdm-remote-session-uccsconfigure (need to look at it but I guess 
it shouldn't be hard)
- update-notifier
- ubuntu-release-upgrader-gtk
- unity (for config migration purpose I guess)

That's a reasonable list to work through

Sebastien Bacher