Code review comment for lp://staging/~jkakar/publish-bot/channel-password

I discovered an interesting problem with this branch. It adds the
channel password by introducing another colon in the format. This
causes old publish-bot's, or other code (such as mup) that understand
the publish-bot protocol, to print messages where every line starts
with a colon.

I wonder if I should, instead of using a colon, represent the channel
and password as <channel>|<password>, or something. And then split
the channel name on '|' to see if there's a password.