Ticket 436 - nsds5ReplicaEnabled can be set with any invalid values.
    
    Bug Description:  There is no checking of the value for nsds5ReplicaEnabled either
                      at startup or with ldapmodify.
    
    Fix Description:  Verify the value is either "on" or "off", and report the
                      appropriate error message.
    
    https://fedorahosted.org/389/ticket/436