mod_http_oauth2: Add TODO about disabling password grant Per recommendation in draft-ietf-oauth-security-topics-23 it should at the very least be disabled by default. However since this is used by the Snikket web portal some care needs to be taken not to break this, unless it's already broken by other changes to this module.

This module discards typing notifications sent to a bare host JID,
preventing error replies to be sent. These errors are harmless but can
be annoying sometimes if your client shows them prominently.