imap-send: use parse options API to determine verbosity

The -v/-q options were sort-of supported but without using the
parse-options API, and were not documented.

Signed-off-by: Bernhard Reiter <ockham@raz.or.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'br/imap-send-verbosity' into pu

* br/imap-send-verbosity:
  imap-send: use parse options API to determine verbosity