Awestruct build environment for Hibernate websites

Building this image

Just run docker build . to build the image locally.

Pushing a tag to the git repository will trigger a build on our repository on quay.io.

If you need to update dependencies:

update the Gemfile
run ./update-gemfile.sh (this will update Gemfile.lock in particular)
optionally:
- build the image with the Gemfiles updated using docker build .
- test the image
commit the changes and tag them as necessary