[RUBY-53] add LoadBalancingPolicy#teardown
verify all load balancing policy methods
implement missing method in scenario
Merge pull request #45 from datastax/load-balancing-policy-teardown

[RUBY-53] add LoadBalancingPolicy#teardown
add public method to refresh schema metadata
allow disabling automatic schema synchronization
update ccm harness
close cluster if available
introduce delayed schema change event processing