Fix pep8 warnings

synapse/api/__init__.py

synapse/api/constants.py

synapse/api/errors.py

synapse/app/__init__.py

synapse/config/_base.py

synapse/config/database.py

synapse/config/email.py

synapse/config/logger.py

synapse/config/ratelimiting.py

synapse/config/repository.py

synapse/config/server.py

synapse/config/tls.py

synapse/config/voip.py

synapse/crypto/__init__.py

synapse/crypto/context_factory.py

synapse/crypto/keyclient.py

synapse/crypto/keyring.py

synapse/handlers/login.py

synapse/handlers/presence.py

synapse/handlers/register.py