gconf-dbus: Support older daemon returning string for object path
gconf-dbus: Support older daemon returning string for object path

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

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