[accessibility] Button plugin doesn't apply "checked"-property to checkbox/radio button when activated with the keyboard

Created by: Lausselloic

I've seen the #18866 (closed) and I agree. But when the user interact with the keyboard (tab to navigate, space bar to check/uncheck) the checked property don't be updated onto radio and checkboxes. http://v4-alpha.getbootstrap.com/components/buttons/#checkbox-and-radio-buttons