Update $router->currentRouteName() method to $router->current() - Laravel 4.1

While updating to Laravel 4.1 I was getting `Call to undefined method Illuminate\Routing\Router::currentRouteName().` 
According to the docs the method name is changed to `current()`.
Check http://laravel.com/docs/upgrade#upgrade-4.1.

By changing the method to `current()` I don't get the exception anymore so hopefully this fixes the problem.