use socket.io with jsonp-polling. several browsers tested. fixes IE8 issues

src/node/hooks/express/socketio.js

@@ -26,10 +26,13 @@ exports.expressCreateServer = function (hook_name, args, cb) {
     });
   });
 
-
-  //this is only a workaround to ensure it works with all browers behind a proxy
-  //we should remove this when the new socket.io version is more stable
-  io.set('transports', ['htmlfile','xhr-polling']);
+  // the following has been successfully tested with the following browsers 
+  // works also behind reverse proxy
+  // Firefox 14.0.1
+  // IE8 with Native XMLHTTP support
+  // IE8 without Native XMLHTTP support
+  // Chrome 21.0.1180.79
+  io.set('transports', ['jsonp-polling']);
 
   var socketIOLogger = log4js.getLogger("socket.io");
   io.set('logger', {