Remove environment ribbon module

Since odoo-role doesn't allow to un-install modules yet, we need to execute the following steps manually BEFORE running the changes introduced by this MR.

1. Uninstall the web_environment_ribbon module through the UI
2. Access the target machine through SSH
3. $ sudo su - odoo
4. odoo@odoo-capfoguer:~$ cd /opt/odoo
5. odoo@odoo-capfoguer:/opt/odoo$ . ../.odoo_venv/bin/activate
6. pip uninstall odoo11-addon-web-environment-ribbon
7. sudo systemctl restart odoo
8. Execute the provision.yml playbook with the changes introduced by this MR

Still... the module appears in the UI as not installed. I would love to see it gone for good. We'll have to further investigate this.