Updated error message in case of deletion failure.

Made explicit that when the script fails to delete one resource. It
stops and don't try to delete remaining resources.

Change-Id: Ic17a1355351474749e4d636c523afe1a445ff344

ospurge/ospurge.py

@@ -616,6 +616,7 @@ def main():
         sys.exit(CONNECTION_ERROR_CODE)
     except DeletionFailed as exc:
         print "Deletion of {} failed".format(str(exc))
+        print "*Warning* Remaining resources have not been cleaned up"
         sys.exit(DeletionFailed.ERROR_CODE)
 
     if (not args.dry_run) and (not args.dont_delete_project):