should work with /bin/sh and not only with /bin/bash

fixes #78: bareos-config is not portable

Signed-off-by: Marco van Wieringen <marco.van.wieringen@bareos.com>
Fix btape crash on quit.

- Instead of freeing the config before tearing down the whole
  setup only do it when we are really done with the config and
  just before we are about to exit the program.
- don't allocate jcr->comment in butil.c as the setup_jcr function
  already calls new_jcr which also allocated this member and as such
  the memory is leaked and smartalloc complains on exit.

Fixed #91: btape crashes after quit command