Merge branch 'develop' into refresh

CHANGES.rst

README.rst

UPGRADE.rst

synapse/__init__.py

synapse/api/constants.py

synapse/api/errors.py

synapse/config/repository.py

synapse/handlers/_base.py

synapse/handlers/auth.py

synapse/handlers/identity.py

synapse/handlers/room.py

synapse/push/__init__.py

synapse/rest/client/v1/login.py

synapse/rest/client/v2_alpha/account.py

synapse/rest/client/v2_alpha/register.py

synapse/rest/media/v1/base_resource.py

synapse/rest/media/v1/thumbnail_resource.py

synapse/storage/schema/delta/22/user_threepids_unique.sql

tests/rest/client/v2_alpha/test_register.py