HOTFIX 2014.5 - Allow guest purchase for subscriptions, also quantity fix

Give option to not require the customer to login when they purchase a subscription product. If subscription is purchased this way, set the variable subscription frequency to no renewal. Also, we corrected an issue where adding a product as a subscription product, one month for instance, and then adding that same product to the cart as a non-renewal, would just update the quantity of the existing cart item. In this example, it would have added a second one month subscription to the cart.