Bug 656515 - Allow Name and Optional UID syntax for grouping attributes
    
    The config validation code in the memberOf plug-in currently requires that the
    grouping attribute be defined to use the Distinguished Name syntax.  The
    uniqueMember attribute is still a common method of grouping users, but this
    attribute is defined to use the Name and Optional UID syntax.  This syntax
    contains a DN plus an optional hex-valued UID that can be appended to the end.
    
    We should allow attribute defined to use the Name and Optional UID syntax to be
    used as memberOf grouping attributes.  We will not support one actually using
    the optional UID portion in the value, but this is extremely rare in practice.