Problems using array parameters on Route::group()

Hey there,

I'm having problems using parameters like 'middleware' on Route::group() facade static method,

And using param 'middleware' like this:
```php
Route::group(['middleware' => 'role:admin'], function () {
Route::post('create','AppointmentController@create');
});
```

The error message is:
`Symfony\Component\Debug\Exception\FatalErrorException: Illuminate\Routing\Router::loadRoutes(): Failed opening required 'Array' (include_path='.:/usr/share/php')`

I'm aware that we can circumvent this problems by using middleware() on each post/get/method, but i was looking for a solution to avoid code duplication.