Add configurations for multi cluster with snitch configuration to Cassandra plugin

[akarasulu]

@eabyshev this is a really important feature that we need ourselves. The multi-cluster configuration works by having multiple clusters across regions like 3 nodes each in 3 regions: total 9 nodes. The clusters in each region are tied to each other using a Cassandra Snitch for synchronization. @absidish can help show you have this is setup.

[akarasulu]

Now we don't have regions but we know how far away peers are from each other or we can treat a peer as a region if it has enough resource hosts to keep the cluster. It will be nice if the user can manage the configuration of cassandra (replication settings) and be able to control how many regions and size of the clusters.