* Check that events pass authentication checks.

Record the list of events that the event passes authentication checks
against.

* Storage functions for event types
* Consume outlier room events

As per RL discussion with Mjark

* A kafkaesque room event consumer for the roomserver.

Implement the main input loop for the roomserver.

It will receive events from a kafkaesque event source and track
where it is in the stream.

It currently does nothing with the events it consumes.