Ticket #207 - [RFE] enable attribute that tracks when a password was last set
    
    Fix description:  Added a new config setting to cn=config: passwordTrackUpdateTime
                      When this is set, we add an operational attribute: pwdUpdateTime
                      to the entry when we modify the userpassword.
    
    https://fedorahosted.org/389/ticket/207
    
    Reviewed by: Noriko!