feat(cluster): rewrite cluster discovering

* Discovering process adapted from EventStore scala client
* Use DNS for first discover but also for reconnoctions (the aim is to be able to reconnect even if all nodes have new IP addresses eg. after rolling update in a cloud environment)
* Being able to perform proper unit testing

src/transport/tcp/tcpConnection.js

@@ -160,4 +160,4 @@ TcpConnection.createConnectingConnection = function(
   return connection;
 };
 
-module.exports = TcpConnection;
+module.exports = TcpConnection;