Tool is only accessible with the container's network, to avoid potential spam/DOS.
Indeed, one could just call the container's public URL with a forged request to redirect POST requests to an arbitrary server.
With this modification, one could still use Filter Hook with an arbitrary URL, but the call should come from Wekan (i.e. mass move/create cards), which is not worth it.

See https://stackoverflow.com/a/42047877

This reverts commit 3acb07b5.

Migrate to Traefik v2

See merge request !53