Updated the Openstack syncroniser to shutdown VM's before deletion. We've seen VM's get stuck in the ERROR state in Nova when they were forcibly deleted rather than shutdown; seemed to be as a result of not releasing resources but we've never found the exact root cause. Contributed by BT and DTU for the NGPaaS EU project

Change-Id: I7cd291fea726c3154f1edfe33d11e5dc006d9ba1
diff --git a/Dockerfile.synchronizer b/Dockerfile.synchronizer
index abc79f6..6c06124 100644
--- a/Dockerfile.synchronizer
+++ b/Dockerfile.synchronizer
@@ -14,7 +14,7 @@
 
 # xosproject/openstack-synchronizer
 
-FROM xosproject/xos-synchronizer-base:2.1.9
+FROM xosproject/xos-synchronizer-base:2.1.18
 
 COPY xos/synchronizer /opt/xos/synchronizers/openstack
 COPY VERSION /opt/xos/synchronizers/openstack/