main: allow for overriding data store location with -data switch
main: allow for overriding data store location with -data switch

Add -data command line switch for passing the location of mender state
data. The setting defaults to /var/lib/mender.

Signed-off-by: Maciej Borzecki <f609d9f713abcd5f8f0e51f08dc151638a7681e7@open-rnd.pl>

bboozzoo/mender,bboozzoo/mender