Sharding:
* Sharding: add actor flag to sharding group for app help
* Sharding: ensure rpcClient is not nil before calling Close()
* Sharding: revert shardingcmd.go comments
* Sharding: more address Str() fixes
Former-commit-id: 0b3d8b73ac1b20eb5c018a71be1d935a1fb860ef [formerly 6cd1df472713e95f6b9f8a0a7b6bbd88a5dd2ca2]
Former-commit-id: 90c7e1a70d46c1f889576a7f2f253a02414c3654