Ticket 495 - internalModifiersname not updated by DNA plugin
    
    Bug Description:  If you are using the "nsslapd-plugin-binddn-tracking", and the DNA plugin
                      modifiers the entry, the internalmodifiersname is not updated.
    
    Fix Description:  This is because the DNA plugin directly modifies the entry, and does not
                      use the internal modify functions that would trigger the last mod attributes
                      to be updated.  So we have to call the last mod update function directly from
                      the dna plugin.
    
                      There is also a slight change to the behavior now.  The internalModifiersname &
                      internalCreatorsname will never be the bind dn, but instead it will be the plugin
                      that actually did the update.  So if a entry was not touched by a DS plugin, then
                      the "database" plugin would be the internal modifier/creator:
    
                                    cn=ldbm database,cn=plugins,cn=config
    
                      This would also allow us to detect if someone replaced the default backend.
    
    https://fedorahosted.org/389/ticket/495
    
    Reviewed by: nhosoi & richm(Thanks!)