Build separate image for the final site

Build just the HTML that's to be served on the site.

This could potentially be done via a Docker volume, such that we can build into the base image if we want, but otherwise it can be via a volume.

assigned to @jamietanna

removed assignee

mentioned in issue #64 (closed)

assigned to @jamietanna

mentioned in issue #133

mentioned in issue #134

mentioned in issue #137 (closed)

mentioned in merge request !57 (merged)

closed

Closed with !55 (merged) merged.