There are some users used original default cluster_name 'Test Cluster', they will fail to start the node for cluster_name change if they use new scylla.yaml. 'ScyllaDB Cluster' isn't more beautiful than 'Test Cluster', reset back to original old to avoid problem for users. Fixes #3060 Signed-off-by: Amos Kong <amos@scylladb.com> Message-Id: <8c9dab8a64d0f4ab3a5d6910b87af696c60e5076.1513072453.git.amos@scylladb.com>