fix for 3804 : improve replication monitoring

These changes improve the replication monitoring by
- changing the monitoring tree so that the monitoring entries use the
  same topology as the current replication topology :
  For example :
  if the topology is currently 2 DS connected to 1 RS and 1RS
  without any DS connected, the monitoring tree will consist
  in a RS entry with 2 DS child entries and 1 RS child entry.
- rename the base-dn attribute into domain-name
- fix the DN of the monitoring entries so that comma and equals signs
  are not used anymore in the RDN.
- group all the replication monitoring entries below cn=replication
  and all the DS and RS entries below a suffix entry