Fixed Bug #PNM-1925 - Added correct version check before calling Cart::getGiftWrappingPrice() method

getGiftWrappingPrice() method was added in Prestashop version 1.5.3.1 and hence it is not available for all 1.5.x versions before that. I have modified the code to use getGiftWrappingPrice() only for version 1.5.3.1 and above.