Handle "on" or "observe" listener method

Signed-off-by: Kris Zyp <kriszyp@gmail.com>

lib/pintura.js

@@ -70,7 +70,7 @@ exports.JsgiApp = JsgiApp;
 var Connector = require("tunguska/connector").Connector;
 exports.addConnection = exports.app.addConnection = function(connection){
 	Connector("local-workers", connection);
-	connection.on("message", function(message){
+	connection[connection.on ? "on" : "observe"]("message", function(message){
 		if(message.method && message.method !== "subscribe"){
 			exports.directApp(message);
 		}