consumer端zk断开重连后调不通provider服务

[jack15083]

What happened:
开发环境zk不太稳定，经连接经常断开发现一断开重连所有的consumer references 就调不能通了，必须重启才能调通，重启consumer端或重启服务端都可以

What you expected to happen:

How to reproduce it (as minimally and precisely as possible):

Anything else we need to know?:
调试发现invokers服务被清空

[jack15083]

zk 监听逻辑这里 zk连接丢失不应该close，这样会导致整个zk监听 goroutine exit掉，服务就会一直调不通了，这里应该改成重连比较好

[Patrick0308]

@jack15083 we handle zookeeper reconnect in HandleClientRestart function in remoting/zookeeper/facade.go:44. Please supply a simple demo to reproduce this issue.

[jack15083]

@jack15083 we handle zookeeper reconnect in HandleClientRestart function in remoting/zookeeper/facade.go:44. Please supply a simple demo to reproduce this issue.
只要报zk connect is nil 这个问题必现

[jack15083]

@jack15083 we handle zookeeper reconnect in HandleClientRestart function in remoting/zookeeper/facade.go:44. Please supply a simple demo to reproduce this issue.

你可以强制将服务端的zk连接断掉，然后重连，消费端这个报错会必现

[jack15083]

#985