[#32721] Fix small error in application view

This error return a PHP Notice:

PHP Notice: Undefined offset: 3 in .../administrator/components/com_config/controller/application/save.php on line 112

Tracker: #32721

http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=32721&start=0