status: Clean up imports

https://bugzilla.gnome.org/show_bug.cgi?id=680426

js/ui/status/keyboard.js

@@ -1,12 +1,9 @@
 // -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
 
-const Clutter = imports.gi.Clutter;
-const GdkPixbuf = imports.gi.GdkPixbuf;
 const Gio = imports.gi.Gio;
 const GLib = imports.gi.GLib;
 const GnomeDesktop = imports.gi.GnomeDesktop;
 const Lang = imports.lang;
-const Mainloop = imports.mainloop;
 const Shell = imports.gi.Shell;
 const St = imports.gi.St;