Also deal with single args correctly
Also deal with single args correctly

The -a option for the "new" command was set to multiple=False, which is
why the callback would recieve a single calendar (as single string)
instead of a tuple of calendars.

pimutils/khal,hobarrera/khal,sheeprine/khal,pdav/khal,sithglan/khal,dzoep/khal,sheeprine/khal,sdx23/khal,sithglan/khal,geier/khal