ChanServ bugfixes for +z and addbans in suspended channels

If ChanServ should use MODE_REGISTERED, update that when moving channels.

Do not check for bans against an auth'ing user in suspended channels.

Change the example entries for off_channel and use_registered_mode to
make the enabled/on values more obvious.
git-archimport-id: srvx@srvx.net--2004-srvx/srvx--devo--1.3--patch-80