Prevent Monasca Notification using YAML mode

If the config option is not specified Monasca Notification defaults
to YAML config parsing and fails to load.

Partially-Implements: blueprint monasca-roles
Change-Id: Id85d9765df525b34d43a77a9e4045e0de19aef99

ansible/roles/monasca/templates/monasca-notification/monasca-notification.json.j2

 {
-    "command": "monasca-notification /etc/monasca/notification.conf",
+    "command": "monasca-notification --config-file /etc/monasca/notification.conf",
     "config_files": [
         {
             "source": "{{ container_config_directory }}/notification.conf",