code: public final RequestToken revokeAll(Grant grant, String role, BaasHandler<Void> handler) {
          return grantAll(grant, role, RequestOptions.DEFAULT, handler);
      }
docs: Asynchronously revokes the access <code>grant</code> to this object from users with <code>role</code>.
  The outcome of the request is handed to the provided <code>handler</code>.
  
  @param grant   a non null {@link com.baasbox.android.Grant}
  @param role    a non null username
  @param handler an handler that will receive the outcome of the request.
  @return a {@link com.baasbox.android.RequestToken} to manage the asynchronous request