Autofill username in link to upgrade products

You can Autofill links for SellApp, making it far more convenient for users and less chance of spacing/formatting of username being an issue.

https://shop.restorecord.com/product/premium?additional-4085c60735770cdb133e54cded7d1960=yourUsernameHere

https://shop.restorecord.com/product/business?additional-4085c60735770cdb133e54cded7d1960=yourUsernameHere

Thanks, I added it.