ChanServ: Service for persisting settings and modes for channels

ChanServ doesn't have permission to set the mode.  You can do one of two things here:
- Have the server (`self.ircd.serverID`) set the mode.
- Implement the "channelstatusoverride-o" action and return `True` when ChanServ is the setter to give ChanServ permission to set this regardless of its channel status.