Updated Application.php for ApiProblem on HTTP Basic

Application.php

<?php

namespace KnpU\CodeBattle;

// ...

class Application extends SilexApplication
{
    // ...

    private function configureSecurity()
    {
        $app = $this;

        $this->register(new SecurityServiceProvider(), array(
            // ... no changes
        ));

        // register this service, so we can share it
        $app['security.entry_point'] = $app->share(function() use ($app) {
            return new ApiEntryPoint($app['translator'], $app['api.response_factory']);
        });
        // setup the HttpBasic "api" firewall to use this entry point
        $this['security.entry_point.api.http'] = $app->share(function() use ($app) {
            return $app['security.entry_point'];
        });

        // setup our custom API token authentication
        $app['security.authentication_listener.factory.api_token'] = $app->protect(function ($name, $options) use ($app) {
            // no changes

            // make this use the security.entry_point service
            // the class that decides what should happen if no authentication credentials are passed
            $this['security.entry_point.'.$name.'.api_token'] = $app->share(function() use ($app) {
                return $app['security.entry_point'];
            });

            return array(
                // ...
            );
        });

        // ...
    }
}