Merge branch 'develop' into http_client_refactor

synapse/api/auth.py

synapse/api/errors.py

synapse/api/events/__init__.py

synapse/api/events/validator.py

synapse/app/homeserver.py

synapse/app/synctl.py

synapse/crypto/event_signing.py

synapse/crypto/keyring.py

synapse/federation/replication.py

synapse/federation/units.py

synapse/handlers/_base.py

synapse/handlers/directory.py

synapse/handlers/events.py

synapse/handlers/federation.py

synapse/handlers/message.py

synapse/handlers/presence.py

synapse/handlers/profile.py

synapse/handlers/register.py

synapse/handlers/room.py

synapse/http/content_repository.py