Implement rate-limiting

http://www.vinaysahni.com/best-practices-for-a-pragmatic-restful-api#rate-limiting
Maybe as a follow up we could move the flood control of the [base_auth](https://github.com/Gizra/restful/blob/b6c9419814210bd1386ce069aa83ca00f4f3478d/plugins/authentication/RestfulAuthenticationBasic.class.php#L31) to use rate-limit, so we consolidate it to a single place