Switch apache debian image to hardened image

[fzipi]

I guess that now that docker is doing hardened images, we could switch the main debian image to be hardened as the alpine one has minimal cves normally.

See https://hub.docker.com/hardened-images/catalog/dhi/httpd/guides

We might need some basic changes:

• decouple the runtime image from the "build" image
• the hardened image already run with the www-data user, using port 8080
• we need to pull from docker-image://dhi.io/httpd:${httpd-version} and docker-image://dhi.io/httpd:${httpd-version}