* Process incoming poll tallies update
* Send Update on poll vote
* Do not send Updates for a poll more often than once every 3 minutes
* Include voters in people to notify of results update
* Schedule closing poll worker on poll creation
* Add new notification type for ending polls
* Add front-end support for ended poll notifications
* Fix UpdatePollSerializer
* Fix Updates not being triggered by local votes
* Fix tests failure
* Fix web push notifications for closing polls
* Minor cleanup
* Notify voters of both remote and local polls when those close
* Fix delivery of poll updates to mentioned accounts and voters
