Merge pull request #664 from Howie66/develop

NOTICE

cluster/cluster_impl/available_cluster.go

cluster/cluster_impl/broadcast_cluster.go

cluster/cluster_impl/broadcast_cluster_invoker.go

cluster/cluster_impl/failback_cluster.go

cluster/cluster_impl/failback_cluster_invoker.go

cluster/cluster_impl/failfast_cluster.go

cluster/cluster_impl/failfast_cluster_invoker.go

cluster/cluster_impl/failover_cluster.go

cluster/cluster_impl/failover_cluster_invoker.go

cluster/cluster_impl/failover_cluster_test.go

cluster/cluster_impl/failsafe_cluster.go

cluster/cluster_impl/failsafe_cluster_invoker.go

cluster/cluster_impl/forking_cluster.go

cluster/cluster_impl/forking_cluster_invoker.go

cluster/cluster_impl/mock_cluster.go

cluster/cluster_impl/registry_aware_cluster.go

cluster/cluster_impl/registry_aware_cluster_invoker.go

cluster/loadbalance/consistent_hash.go

cluster/loadbalance/least_active.go