Merge branch 'release-v0.19.3' of github.com:matrix-org/synapse

CHANGES.rst

README.rst

contrib/cmdclient/console.py

contrib/example_log_config.yaml

contrib/systemd/synapse.service

docs/CAPTCHA_SETUP.rst

jenkins-dendron-haproxy-postgres.sh

jenkins-dendron-postgres.sh

scripts/synapse_port_db

synapse/__init__.py

synapse/api/constants.py

synapse/app/synchrotron.py

synapse/config/tls.py

synapse/federation/federation_client.py

synapse/federation/transaction_queue.py

synapse/handlers/admin.py

synapse/handlers/device.py

synapse/handlers/federation.py

synapse/handlers/presence.py

synapse/handlers/room_member.py