Fix middleware call

[FelipeUmpierre]

I was having trouble to use middleware

$router->post("/register/save", "Controller\RegisterController@save", "Middleware\RegisterMiddleware@validate");

I was getting this errors:

Notice: Trying to get property of non-object ... Router.php on line 221
Warning: call_user_func_array() expects parameter 1 to be a valid callback, no array or string given ... Router.php on line 221

So I use the example 1 from php.net

I am using PHP version: 5.5.12