Update nginx config to pass parameters to Slim

I have updated the nginx config for Slim as per: https://github.com/codeguy/Slim#nginx

With this change you can access the $_GET parameters via Slim

```php
$app->get('/test', function () use ($app) {
    $allGetVars = $app->request->get();
    print_r($allGetVars);
});
```

A HTTP request to the following `/test?hello=123&world=321` will now output the expected result:

```
Array
(
    [hello] => 123
    [world] => 321
)
```

Without this change, the `/test` route would not even be triggered.