Add Continuous Deployment support - better CI/CD integration

[thomvaill]

As mentioned in the README, I did not have time to develop this feature properly yet.

I used to do CD with a T.A.D.S. similar repository by (roughly):

• Always referer to Docker images with tags
• Manage those tags into a separate tags.yml file
• Write a script that can update a tag, perform a ./tads ansible-playbook production deploy, and in case of success commit and push the file
• Make the CI/CD tool use this script in the deployment pipeline

We may also consider the option of using Portainer's API to achieve CD.
But I'm not really in favor of this because the main advantage of commiting the newly deployed tags is that all developers can stay in sync with the prod.