* move simple_async_mock to test_utils

... so that it can be re-used

* Remove references to `SamlHandler._map_saml_response_to_user` from tests

This method is going away, so we can no longer use it as a test point. Instead,
factor out a higher-level method which takes a SAML object, and verify correct
behaviour by mocking out `AuthHandler.complete_sso_login`.

* changelog

* Factor out functions for injecting events into database

I want to add some more flexibility to the tools for injecting events into the
database, and I don't want to clutter up HomeserverTestCase with them, so let's
factor them out to a new file.

* Rework TestReplicationDataHandler

This wasn't very easy to work with: the mock wrapping was largely superfluous,
and it's useful to be able to inspect the received rows, and clear out the
received list.

* Fix AssertionErrors being thrown by EventsStream

Part of the problem was that there was an off-by-one error in the assertion,
but also the limit logic was too simple. Fix it all up and add some tests.

I got fed up with always adding '@unittest.DEBUG' every time I needed to debug a test.

Add a test to check that get_room_names_and_aliases does the same
thing on both the master and on the slave data store.

synapse

This is necessary for replicating the data in synapse to be visible to a
separate service because presence and typing notifications aren't stored
in a database so won't be visible to another process.

This API can be used to either get the raw data by requesting the tables
themselves or to just receive notifications for updates by following the
streams meta-stream.

Returns updates for each table requested a JSON array of arrays with a
row for each row in the table.

Each table is prefixed by a header row with the: name of the table,
current stream_id position for the table, number of rows, number of
columns and the names of the columns.
This is followed by the rows that have been added to the server since
the requester last asked.

The API has a timeout and is hooked up to the notifier so that a slave
can long poll for updates.

Currently we store all access tokens in the DB, and fall back to that
check if we can't validate the macaroon, so our fallback works here, but
for guests, their macaroons don't get persisted, so we don't get to
find them in the database. Each restart, we generate a new ephemeral
key, so guests lose access after each server restart.

I tried to fix up the config stuff to be less insane, but gave up, so
instead I bolt on yet another piece of custom one-off insanity.

Also, add some basic tests for config generation and loading.

fix the copyright holder from matrix.org to OpenMarket Ltd, as matrix.org hasn't been incorporated in time for launch.