Replace on with timestamp as the checkbox value

In the default view. This will allow us to validate the timestamp
when making actions in the publish list view.

Re a45a9c3

symphony/content/content.blueprintssections.php

@@ -54,7 +54,7 @@ public function __viewIndex()
                 $td1->appendChild(Widget::Label(__('Select Section %s', array(General::sanitize($s->get('name')))), null, 'accessible', null, array(
                     'for' => 'section-' . $s->get('id')
                 )));
-                $td1->appendChild(Widget::Input('items['.$s->get('id').']', 'on', 'checkbox', array(
+                $td1->appendChild(Widget::Input('items['.$s->get('id').']', $s->get('modification_date'), 'checkbox', array(
                     'id' => 'section-' . $s->get('id')
                 )));