Connection: once->on in case of multiple socket errors

lib/Connection.js

@@ -136,7 +136,7 @@ Connection.prototype.connect = function() {
     err.source = 'socket';
     self.emit('error', err);
   };
-  this._sock.once('error', this._onError);
+  this._sock.on('error', this._onError);
 
   socket.once('close', function(had_err) {
     clearTimeout(self._tmrConn);