Add Wasta 14 keyboard handling via IBus alone

Produces a list of available keyboards properly, but doesn't attempt
to switch keyboards.  The code is adapted from the combined keyboard
handling written to support Trusty.  It's too bad the two systems went
their separate ways in this area.
has been deprecated since version 2.36 (may be a problem in the future?)
https://developer.gnome.org/gobject/unstable/gobject-Type-Information.html#g-type-init