Add Github Actions

[maslick]

• This PR adds a simple CI job with Github Actions, which runs integration tests
• A couple of improvements:
  • Activate the it profile with -Dit=true
  • Default value for docker_host is implicitly set to unix:///var/run/docker.sock, which should work out of the box on Unix & Mac OSX (see documentation)
  • docker_host can be overridden with: -Ddocker_host=tcp://192.168.59.103:2375