Implement dual queue fix---register for all events in messages queue.
Implement dual queue fix---register for all events in messages queue.

We now receive some duplicate events, but we decided this was the best
way to avoid race conditions between the two event queues. All event
applications from the event queues must be idempotent.

zulip/zulip-ios,zulip/zulip-ios,knowcliu/zulip-ios,knowcliu/zulip-ios