uc_ajax_cart does not support varprice or other modules that extend the add to cart form

Some modules implement hook_form_alter and modify any form that matches 'uc_product_add_to_cart_form_####'. The uc_ajax_cart module does not send the proper form_id in the uc_ajax_cart_add_item function.

The drupal_execute function should be modified to be

drupal_execute($data['form_id'], $formValues, $product );