Add matching Kindle by device name or volume label

Signed-off-by: Mikhail Gusarov <dottedmag@dottedmag.net>
Update TODO

Signed-off-by: Mikhail Gusarov <dottedmag@dottedmag.net>
Split copier.do_copy

It used to match files, match Kindles and do copying.
Split into 3 functions.

Signed-off-by: Mikhail Gusarov <dottedmag@dottedmag.net>