It's used in both American and British English (unfortunately). This isn't a standard form, so it doesn't matter too much where the apostrophe goes. In theory there should be two apostrophes - one before and one after the 'n', to represent the missing 'a' and the missing 'd'. Personally, I hate this form. It's old-fashioned and 'cheesy', and tends to be used in product names, particularly of snacks and convenience foods. It makes me cringe. It's one of those forms which you should be aware of, and recognise when you see it, but you should avoid using.