Deploy assets.dereckson.be

Summary:
The Nasqueron infrastructure hosts external websites on Ysul.

These websites are welcome to use the "legacy-webserver" role
to deploy files to /var/wwwroot.

For paths, we use the TLD/subtld/domain/subdomain syntax to circumvent
the following issue: https://github.com/saltstack/salt/issues/4610

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D1011