notificationDaemon, magnifierDBus: port to GDBus

Move /org/freedesktop/Notifications and /org/gnome/Magnifier to the
GDBus connection, so they're matched with the appropriate DBus name.

https://bugzilla.gnome.org/show_bug.cgi?id=648651

js/ui/magnifierDBus.js

@@ -1,6 +1,7 @@
 // -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
 
 const Gio = imports.gi.Gio;
+const GLib = imports.gi.GLib;
 const Main = imports.ui.main;
 
 const MAG_SERVICE_NAME = 'org.gnome.Magnifier';