Pin Traefik Docker image to v1
Until we do the required changes to update to v2.
Fixes
-FROM traefik:alpine
+FROM traefik:1.7-alpine
RUN mkdir -p /etc/traefik/acme
RUN touch /etc/traefik/acme/acme.json
RUN chmod 600 /etc/traefik/acme/acme.json
