Private demo

This builds an image that has the demo integrations enabled. This is used for app verification and deployed with https://github.com/home-assistant/deployments

Updates

To change the configuration which is used by the instance, adjust the rootfs/etc/config/configuration.yaml file.
To change the version of Home Assistant that is used, adjust the first line in the Dockerfile file.

After a change is merged, create a release of the repository to publish a new image. After the image is published, the deployment can be updated.