gconf-database-dbus: Fix notify listeners to also use an object path
gconf-database-dbus: Fix notify listeners to also use an object path

Fixes: https://bugzilla.gnome.org/show_bug.cgi?id=655656

hyperair/gconf-gdbus,GNOME/gconf,GNOME/gconf,hyperair/gconf-gdbus,hyperair/gconf-gdbus,hyperair/gconf-gdbus,GNOME/gconf,GNOME/gconf