Implement proper provisioning for gvaldap

- merge improvements from the internal saltstack repository
- define dummy secrets in the pillars
- use systemd to setup the gvaldap celery worker

states/gnuviechadmin/celery-worker.service

@@ -0,0 +1,12 @@
+[Unit]
+Description={{ description }}
+
+[Service]
+EnvironmentFile=-/etc/default/{{ appname }}
+ExecStart={{ virtualenv }}/bin/celery worker -A {{ celery_module }} -Q {{ amqpname }} --loglevel=INFO
+Restart=on-failure
+User={{ app_user }}
+WorkingDirectory={{ checkout }}/{{ appname }}
+
+[Install]
+WantedBy=multi-user.target