feat(docker, front): cleaner & more reproducible frontend
- The frontend dependencies are now cached in the docker images itself
- A little hack is used to restore them when needed
node_modulesfolder is stored outside of the workdir and then brought in
- Images are now versioned on the registry
- The docker-compose file has been updated to use the new/versioned images.
- The documentation has been updated.
- And the Gitlab-CI has been tweaked.