ApiController - move exceptions map to rest.yml

[benedyktdryl]

public function exceptionAction($type)
    {
        $serializer = $this->container->get('serializer');

        /* move to rest.yml */
        $map = array(
            'not_authenticated' => array(
                'message'   => 'Not authenticated',
                'code'      => 401
            )
        );

        $response = array('message' => $map[$type]['message']);

        return new Response(
            $serializer->serialize($response, 'json'), 
            $map[$type]['code']
        );
    }