Merge remote-tracking branch 'origin/develop' into develop

docs/specification.rst

synapse/api/auth.py

synapse/handlers/__init__.py

synapse/handlers/admin.py

synapse/rest/__init__.py

synapse/rest/admin.py

synapse/rest/register.py

synapse/server.py

synapse/storage/__init__.py

synapse/storage/registration.py

synapse/storage/schema/delta/v5.sql

synapse/storage/schema/users.sql

tests/rest/test_presence.py

tests/rest/test_profile.py

tests/rest/test_rooms.py

tests/storage/test_registration.py

tests/utils.py