Allow other roles than Owner to be catalogued in a monovalued column.

Monovalued column only index user ID, and no security group.
If some security groups are assigned to such role, they are still catalogued in
the roles_and_users table.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@25449 20353a03-c40f-0410-a6d1-a30d3c3de9de