Move all the wrapper functions for distributor.fire

Move the functions inside the distributor and import them
where needed. This reduces duplication and makes it possible
for flake8 to detect when the functions aren't used in a
given file.

Call profile handler get_displayname directly

Add LDAP authentication

Add tests for redactions

Add tests for get_latest_event_ids_in_room and get_current_state

Rather than adding them globally. This limits the changes to only
affect the tests.

Deduplicate membership changes

Signed-off-by: Christoph Witzany <christoph@web.crofting.com>

Set profile information when joining rooms remotely

Let users see their own leave events

Test that room membership is replicated

Add a slaved events store class

... otherwise clients get confused.

Fixes https://matrix.org/jira/browse/SYN-662,
https://github.com/vector-im/vector-web/issues/368

Don't require config to create database

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.

Move _get_cache_dict into the SQLBaseStore