[WIP] Added 404 header support

When wordpress will return a 404 header, this PR allows symfony to return the correct status code instead of 200
We still need to have a global wordpress object to avoid global statement and only have them in a dedicated location.

```php
<?php

class Wordpress {
    public function hasQuery()
    {
         global $wp_query;

        return !$wp_query ;
    }
}
```