client: added disconnect method

lib/client.js

@@ -62,6 +62,22 @@ Client.prototype.connect = function(name){
   });
 };
 
+/**
+ * Disconnects from all namespaces and closes transport.
+ *
+ * @api private
+ */
+
+Client.prototype.disconnect = function(){
+  var socket;
+  // we don't use a for loop because the length of
+  // `sockets` changes upon each iteration
+  while (socket = this.sockets.shift()) {
+    socket.disconnect();
+  }
+  this.close();
+};
+
 /**
  * Removes a socket. Called by each `Socket`.
  *