Add option to start window manager with chrome

On installations where XBMC/Kodi are running standalone, chrome often will not display correctly due to the lack of a window manager. 
It would be good to detect installed window managers: https://github.com/ghost1227/cdm/blob/master/src/cdm#L91
List them in settings, then start the selected one before/alongside chrome, killing it once chrome quits.
