Ticket 589 - RFE - Support RFC 4527 Read Entry Controls
    
    Description:  Add support for read entry controls.  The pre-read control
                  returns a copy of the entry before it was modifed, and the
                  post-read control returns the entry after the modify.  Both
                  controls can be used for the same operation.  The control
                  is added just before the result is returned to the client.
    
    https://fedorahosted.org/389/ticket/589
    
    Reviewed by: Noriko & Rich(Thanks!!)