Allow updating cassandra cluster name from bosh deployment

[bgandon]

Currently, modifying the cluster_name property in a BOSH deployment doesn't lead to an actual change of the cluster name on the deployed Cassandra nodes.

Here is an example of the steps to apply:

cqlsh -e "UPDATE system.local SET cluster_name = '<new_cluster_name>' WHERE key='local';"

nodetool flush system

sed -i -e 's/<old_cluster_name>/<new_cluster_name>/' cassandra.yaml # Update cluster_name in 'cassandra.yaml' config

monit stop cassandra && monit start cassandra # See <https://bosh.io/docs/bpm/runtime/#instant-restart>

cqlsh -e "SELECT cluster_name FROM system.local;" # should return the <new_cluster_name>

Source: Change Cluster Name in DataStax Support › DataStax Enterprise › General

Related to (but not blocked by) #47.