Use service descriptor instead of port number

This patch fixes a segfault due to a major change to libimobiledevice.
From the libimobiledevice git repo:

  commit fcc1bb855efb6860417ed827d3b50feba24a9a8b
  Author: Martin Szulecki <opensuse@sukimashita.com>
  Date:   Tue Feb 26 03:20:56 2013 +0100

  Refactor port number use into service descriptor to enable SSL for
  services

  This is a major change which breaks API but is required in order to
  support SSL communication for services as used by network connections.