fixes #1854 use new icons

After updating fontello I put the right icons as on the mockup for core and system

admin/maintenance_sys.php

@@ -59,7 +59,7 @@ if (is_webmaster())
       switch ($rows['object_id'])
       {
         case ACTIVITY_SYSTEM_CORE:
-          $object_icon = 'icon-heart';
+          $object_icon = 'icon-piwigo';
           $object = l10n('Core');
 
           switch ($rows['action'])

admin/themes/default/js/maintenance_sys.js

@@ -24,7 +24,7 @@ function line_constructor(line){
 
     // Display Username
     'System' == line.username
-    ? new_line.find('.icon_user').addClass('icon-wrench')
+    ? new_line.find('.icon_user').addClass('icon-robot-head')
     : new_line.find('.icon_user').addClass(color_icons[line.user_id % 5]).html(initial_user);
     new_line.find('.text_username').text(line.username).attr('title', line.username);