workadventure: use docker-compose from debian

roles/workadventure/meta/main.yml

@@ -2,5 +2,4 @@
 
 dependencies:
 - { role: acertmgr }
-- { role: docker }
 - { role: nginx, nginx_ssl: True }

roles/workadventure/tasks/main.yml

@@ -3,6 +3,9 @@
 # TODO
 # source code is not yet checked out from git
 
+- name: Install docker-compose
+  apt: name=docker-compose
+
 - name: Install systemd unit
   template: src=workadventure.service.j2 dest=/lib/systemd/system/workadventure.service
   notify: