adding cassandra write level config to the doc

git-svn-id: https://svn.apache.org/repos/asf/incubator/sirona/trunk@1541048 13f79535-47bb-0310-9956-ffa450edef68
using right wrapper type to create JMX operations

git-svn-id: https://svn.apache.org/repos/asf/incubator/sirona/trunk@1541049 13f79535-47bb-0310-9956-ffa450edef68