Default load balancing policy should match the Java driver and be tokenaware

The default load balancing policy for the java driver is

public static LoadBalancingPolicy defaultLoadBalancingPolicy()
{ // Note: balancing policies are stateful, so we can't store that in a static or that would screw thing // up if multiple Cluster instance are started in the same JVM. return new TokenAwarePolicy(new DCAwareRoundRobinPolicy()); }

but for the python driver it's the rather unfortunate RoundRobinPolicy

https://github.com/datastax/python-driver/blob/master/cassandra/policies.py