send system notification on period confirmation

src/Bundle/ChillMainBundle/Resources/views/Notification/extension_list_notifications_for.html.twig

@@ -1,7 +1,11 @@
 <div class="list_notification_for">
     {% for notification in notifications %}
         <div class="notification {% if notification.isReadBy(app.user) %}read{% else %}unread{% endif %}">
-            <div>{{ 'notification.you were notified by %sender%'|trans({'%sender%': notification.sender|chill_entity_render_string }) }}</div>
+            {% if not notification.isSystem %}
+                <div>{{ 'notification.you were notified by %sender%'|trans({'%sender%': notification.sender|chill_entity_render_string }) }}</div>
+            {% else %}
+                <div>{{ 'notification.you were notified by system'|trans }}</div>
+            {% endif %}
             <div>
                 <ul class="record_actions_small">
                     <li>