[xmonad] Xmonad-contrib AppLauncher

The XMonad AppLauncher doesn't work properly with filenames with spaces. It seems to be because it uses the 'spawn' function from core. I replaced the spawn with safeSpawn from XMonad.Utils.Run for my instance, but I'm not sure how it would affect the "grand plan". I also can't make a patch since the tests fail on -fglasgow-exts.