Merge pull request #1875 from matrix-org/erikj/fix_email_push

synapse/handlers/auth.py

synapse/handlers/register.py

synapse/push/mailer.py

synapse/rest/client/v1/login.py

synapse/rest/client/v2_alpha/register.py

synapse/server.py

tests/handlers/test_auth.py

tests/handlers/test_register.py