imapd -U in cyrus.conf

[Rob Mueller]

> We also wanted to use -U 1 so we could be sure changes to imapd.conf
> would be used more quickly since there wouldn't be imapd procs hanging
> around with old settings.

FYI, another way of doing this without forcing -U 1 is to touch the imapd 
executable file.

The cyrus master notices if the executable file mod time on disk has 
changed, and when the user logs off or disconnects from the imapd, it'll 
terminate it.

Rob