Revert "support admin_email config and pass through into blocking errors, return AuthError in all cases"

This reverts commit 0d43f991.

This is the first tranche of support for room versioning. It includes:
 * setting the default room version in the config file
 * new room_version param on the createRoom API
 * storing the version of newly-created rooms in the m.room.create event
 * fishing the version of existing rooms out of the m.room.create event

Returns an M_CONSENT_NOT_GIVEN error (cf
https://github.com/matrix-org/matrix-doc/issues/1252) if consent is not yet
given.

turns out we need to reuse this, so it's better in the config class.

When a user first syncs, we will send them a server notice asking them to
consent to the privacy policy if they have not already done so.

The imports were shuffled around a bunch in py3

Signed-off-by: Adrian Tschira <nota@notafile.com>

These worked accidentally before (python2 doesn't complain if you
compare incompatible types) but under py3 this blows up spectacularly

Signed-off-by: Adrian Tschira <nota@notafile.com>

This has no effect on python2

Signed-off-by: Adrian Tschira <nota@notafile.com>

... instead of creating our own special SQLiteMemoryDbPool, whose purpose was a
bit of a mystery.

For some reason this makes one of the tests run slightly slower, so bump the
sleep(). Sorry.

Configure the connectionpool used for unit tests to run the `on_new_connection`
function.

This isn't used, and looks thoroughly bitrotted.

Add federation_domain_whitelist

gives a way to restrict which domains your HS is allowed to federate with.
useful mainly for gracefully preventing a private but internet-connected HS from trying to federate to the wider public Matrix network

Fix flakiness in the UTs caused by the user_directory being updated in the
background

what could possibly go wrong

- allows sysadmins the ability to lock down their servers so that people can't
send their users room invites.

Instead of every time a new email pusher is created, as loading jinja2
templates is slow.