Ability to hide real userids in "Other Users" namespace

[Alexander Drozdov]

Hello!

I have made the patch of cyrus imapd server that adds ability
to the server to hide real users identifiers in "Other Users"
namespace (altnamespace config option must be enabled). Real
userids are being replaced by other ones which has been fetched
from LDAP server "on the fly".

You can see my current version of the patch and additional
information in the Andrew Bugzilla (bug # 2750):

https://bugzilla.andrew.cmu.edu/show_bug.cgi?id=2750

Alexander Drozdov