Run tests under PostgreSQL (#3423)

.travis.yml

changelog.d/3423.misc

synapse/handlers/presence.py

synapse/storage/client_ips.py

tests/__init__.py

tests/api/test_auth.py

tests/api/test_filtering.py

tests/crypto/test_keyring.py

tests/handlers/test_auth.py

tests/handlers/test_device.py

tests/handlers/test_directory.py

tests/handlers/test_e2e_keys.py

tests/handlers/test_profile.py

tests/handlers/test_register.py

tests/handlers/test_typing.py

tests/replication/slave/storage/_base.py

tests/rest/client/v1/test_admin.py

tests/rest/client/v1/test_events.py

tests/rest/client/v1/test_profile.py

tests/rest/client/v1/test_register.py