Update README to reference 0.8.3.
Update README to reference 0.8.3.

rightscale/cassandra,rightscale/cassandra,stipple/cassandra_new,stipple/cassandra_new,stipple/cassandra_new,cassandra-rb/cassandra,stipple/cassandra_new,cassandra-rb/cassandra,cassandra-rb/cassandra,cassandra-rb/cassandra,rightscale/cassandra