Have TypingNotificationEventSource.get_new_events_for_user() return a deferred, for consistency and extensibility

Neater implementation of membership change auth checks, ensuring we can't forget to check if the calling user is a member of the room

Update syutil version to 0.0.4

Move server key api into rest/key/v1

SYN-339: Cancel the notifier timeout when the notifier fires

Improve get event cache

Hotfixes v0.8.1 r3

Don't yield on notifying all listeners

Fix a notifier leak

Add paranoia checks to make sure that we evict stale NotificationListeners when we are about to process them

Fix bug where we didn't inform the NotificataionListeners about new rooms they have been subscribed to. This meant that the listeners didn't clean themselves up fully from all the dicts

Caused by a bad if check, which incorrectly executes for both 0 and None,
when None was the original intent.

Specifically, the ASes own user ID wasn't being treated as 'exclusive' so
a human could nab it. Also, the HS would needlessly send user queries to the
AS for its own user ID.

Application services registration changes (PR #116)