Create static copy of the front page

[ianb]

We want to take the front page of https://screenshots.firefox.com and turn it into a static page. We don't need any JavaScript, except enough to start the onboarding (look for location.hash).

The static site should go in a new directory, and land in master. The Docker build script should start using the static site (and so dev/stage/prod will get this), while in actual local development the old site will remain (until the full server removal lands).