Provide nginx configuration for ACME DNS

Summary: Ref T1580.

Test Plan:
Deploy with:
salt equatower state.sls_id /etc/nginx/vhosts/acme_dns/acme.conf roles/paas-docker/nginx/config

Browse https://acme.nasqueron.org

Reviewers: dereckson

Reviewed By: dereckson

Maniphest Tasks: T1580

Differential Revision: https://devcentral.nasqueron.org/D2178