Json Output enableJsonExprFinder

enableJsonExprFinder for Zend_Json::encode so you can e.g. define listeners for plugin form elements
$form->setElement(
    'select',
    'mappingFilesPath',
    array(
        'label' => 'Modus',
        'required' => true,
        'store' => array(),
        'listeners' => array(
            'select' => new Zend_Json_Expr('function() { /*code*/ }')
        ),
        'scope' => Shopware\Models\Config\Element::SCOPE_SHOP
    )
);