qmp: Say "out-of-band" instead of "Out-Of-Band"

Affects documentation and a few error messages.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180703085358.13941-2-armbru@redhat.com>
6 files changed