Use Mage_Core_Controller_Front_Action after SUPEE-5994

[Zifius]

trafficstars

See https://github.com/firegento/magento/blob/v1.9.1.1%2Bpatch2/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php#L286

Now there is a strict check for the controller instance class. I'm not sure the impact on this extension but perhaps worth a check