Fix input source switching to work for keyboard keyboard input sources

Currently, the setting that @ybian created in #987 only works for keyboard **layout** input sources, and not keyboard input sources, which means that when activating/deactivating QS it can switch between layouts just fine (i.e. QWERTY to DVORAK or AZERTY - they all use the same latin characters), but it won't work for keyboard input sources (i.e. keyboards with completely different characters Korean or Pinyin)

To see the bug, try this:

* Enable either Korean or Pinyin in the 'Input Sources' keyboard system prefs.
* Go to the command QS prefs, enable the keyboard option and from the dropdown select your actual keyboard (US, British, French etc.)
* Switch the input source to Korean/Pinyin from the Input source menu bar popup
* Invoke QS
* Close QS

You'll notice the layout switches to your selected input source when you invoke QS (great!) but it doesn't switch back when you dismiss QS (not so great).

P.S. Who says I'm not travelling Asia with the sole goal of improving QS support for Asian languages...? ;-)