Upgrade LBCAlerte to version 3.3

Add upgrade script

sources/lib/AdService/SiteConfig/AbstractSiteConfig.php

@@ -35,6 +35,12 @@ abstract class AbstractSiteConfig
      */
     protected $has_date = true;
 
+    /**
+     * Indique si la sauvegarde d'annonce est possible.
+     * @var bool
+     */
+    protected $allow_backup = false;
+
     /**
      * @param string $name
      * @return mixed