Added with_load_balancing_policy, with_reconnection_policy, with_retry_policy to cql_builder.
new policies added: constant_reconnection, dcaware_round_robin, downgrading_consistency, fallthrough_retry.
added one_node_load_balancing_policy to integration tests.
consistency tests for cql_round_robin_policy
dcaware_round_robin_load_balancing_policy added to unit tests
dcaware_load_balancing_policy added to consistency tests
Merge pull request #21 from jacekkasprzak/master

Added the possibility to set new policies to builder. New policies added. New tests ( unit and consistency) of these policies added.