The current way to handle replication, is cumbersome and makes it difficult to properly handle replication topology.

Create a new replication topology subtree under the cn=etc tree that will have a simplified schema to list the replication agreements between servers, and have a global configs for things like excluded replication attributes.

The idea is that admins would change objects in this shared tree and these changes would then be reflected in actual replication agreement changes in cn=config as a consequence.

Advantages (in no particular order):

* it becomes possible to easily visualize the topology w/o having to contact multiple servers
* it is possible to centrally remove a server and have all other server remove the relevant replication agreement w/o having to contact every single server
* it is possible to have a topology checker that uses graph theory
* it is possible to use said checker to prevent split brain situations by simply denying (LDAP_UNWILLING_TO_PERFORM) changes that would break the graph
* it is possible to create new agreements remotely w/o direct access to the replica just by virtue of replication of the shared tree.
* it will be possible to create multiple replication typologies for different database (ie one for main tree and one for CA data) and have distinct checks for all of them.

In the first version, the Web UI should be able to display at least read only graph of the replicas.