Development environment

• devenv configuration to create a LXC container
• Install npm global with yarn (needed by the backend) and pnpm (needed by Etherpad)
• Install PostgreSQL, create the users and the DBs needed by the backend and Etherpad
• Install Etherpad
• Update the README

inventory/host_vars/acoords-test.devs.coop/etherpad.yml

 ---
-<<<<<<< HEAD
 etherpad_url: "https://{{ inventory_hostname }}/etherpad"
 etherpad_ip: "127.0.0.1"
 etherpad_trust_proxy: "true"