Fix unicode database support

synapse/app/homeserver.py

synapse/handlers/login.py

synapse/rest/client/v1/profile.py

synapse/storage/__init__.py

synapse/storage/_base.py

synapse/storage/events.py

synapse/storage/keys.py

synapse/storage/profile.py

synapse/storage/registration.py

synapse/storage/room.py

synapse/storage/schema/full_schemas/11/media_repository.sql

synapse/storage/schema/full_schemas/11/profiles.sql

synapse/storage/schema/full_schemas/11/transactions.sql

synapse/storage/signatures.py

synapse/storage/transactions.py