Merge branch 'develop' into key_distribution

CAPTCHA_SETUP

README.rst

docs/postgres.rst

register_new_matrix_user

scripts/port_from_sqlite_to_postgres.py

static/client/register/style.css

synapse/api/auth.py

synapse/api/constants.py

synapse/api/errors.py

synapse/app/homeserver.py

synapse/config/_base.py

synapse/config/captcha.py

synapse/config/database.py

synapse/config/homeserver.py

synapse/config/logger.py

synapse/handlers/__init__.py

synapse/handlers/_base.py

synapse/handlers/auth.py

synapse/handlers/federation.py

synapse/handlers/identity.py