Merge pull request #2429 from matrix-org/erikj/groups_profile_cache

synapse/groups/groups_server.py

synapse/handlers/__init__.py

synapse/handlers/groups_local.py

synapse/handlers/message.py

synapse/handlers/profile.py

synapse/handlers/register.py

synapse/handlers/room_member.py

synapse/rest/client/v1/profile.py

synapse/server.py

synapse/storage/_base.py

synapse/storage/profile.py

synapse/storage/schema/delta/43/profile_cache.sql

tests/handlers/test_profile.py

tests/handlers/test_register.py

tests/rest/client/v1/test_profile.py