Ref: refactor code in registry.zookeeper, create remoting/zookeeper to code reuse in config_center for zk

* Imp: add Client.GetPendingResponse to limit the lock scope

* Fix: return pkg len as case 1

* Mod: update getty&hessian2 version

* Fix: use bufio.NewReadSize instead of bufio.NewReader

* Fix: return {nil, 0, nil} for tcp case 1

* Fix: return {nil, 0, nil} for tcp case 1 for server handler

Fix:issue #68

Fix bug

Fix: change go-for-apache-dubbo to dubbo-go as issue #74

Mod: change license

Mod: go import dubbo-go path

Fix:library security

Fix: lack SetProviderConfig