Application services transaction reliability (PR #106)

Conflicts:
	synapse/storage/__init__.py

Remember the 'last seen' time for a given user/IP/device combination and only bother INSERTing another if it's stale

Store rearrangement

Add the tiniest of tiny one-element caches to get_room_events_max_id() as it's read every time someone hits eventstream

Allow @cached-wrapped functions to have more or fewer than 1 argument; assert on the total count of them though

Hotfixes v0.8.1 r2

Disable registration by default. Add script to register new users. 

It existed but was hardcoded to True.
Give it an underscore for consistency.
Also don't pull in syweb unless we're actually using the web client.