testing, issue #1766: Add nightly release to docker-ci
testing, issue #1766: Upgrade tooling for Docker nightly release
testing infrastructure, issue #1766: Temporarily install docker with proper apparmor handling
testing, issue #1800: Add Dockerfile for docker in docker testing
testing, issue #1800: separate test_docker.sh code from Dockerfile.
 testing infrastructure, issue #1800: Base docker PRs and commit testing on /Dockerfile
testing infrastructure, issue #1800: Add improvements on dind merge process, github PR processing and reenable coverage testing