Minimal deployment

We have issues with ansible-pull, which seems not able to parse an inventory.

We still have ansible_hostname variable that let us set up a workaround with a variable of dicts with hostnames as keys, to define variables per host.

But in fact, for our present situation where desktops have network access, it is enough if we can start accessing them by ssh, to configure them with classical push ansible architecture. We have all we need for that:

• ufw firewall set up, all closed inconming, all open outgoing,
• install openssh-server and open it to a specific range of values.

Let's build a branch and a tag for thar.