Failure while connecting to zk if HBase is running in standalone mode in a container

With this change zookeeper will only listen for client connections on 127.0.0.1 in standalone mode. If HBase is running in standalone mode inside a docker container and docker port forwarding is being used to connect to HBase inside container then, any client trying to connect to zk will have destination IP as container's private IP rather than loopback IP. This will cause zk to reject all client connections being initiated from outside the container. 

Thus, we need a way to make zk listen for client connections on IP other than loopback. zk already provides a property named `clientPortAddress` to specify the address to listen for client connections. And, we can specify zk properties using `hbase.zookeeper.property.` prefix. Thus, the proposal is to allow user to specify the IP address that zk will listen on using `hbase.zookeeper.property.clientPortAddress` and if its not specified then default to loopback as per current behaviour.

This way, the tests will still remain unimpacted and HBase can also be used in standalone mode in a container.