12.0-dev
tooling: Move email_log.py to development only views.
models: Extract zerver.models.clients.
thumbnail: Do not Camo old thumbor URLs; serve images directly.
devlogin: Filter placeholder realms from a subdomain change.
confirm_email_change: Use redirect-to-POST trick.
requirements: Upgrade Python requirements.
confirmation: Rename REALM_CREATION to NEW_REALM_USER_REGISTRATION.
showroom: Set up devtools/inputs page for showcasing input components.