Following the introduction of its 14-day iTunes refund policy in Europe, Apple has apparently begun clamping down on refund abuse, according to a new report from 9to5Mac. Citing a tweet from developer Rosyna Keller, users who are detected by Apple as abusing the new refund policy will now be presented with a dialog box requiring them to acknowledge that they will no longer be eligible to receive a refund once they have downloaded the item in question.…