Allow creators to choose more default currencies

At the moment you can only choose the default currency to be, either Euro (EUR), Pound Sterling (GBP) or U.S. Dollar (USD). It would be nice to have the ability to choose the default currency to be one of the currencies the user can choose to convert it to/see it as.

This would make it so, for example a Danish Store that primarily is for danish customers can choose to have all their procucts listed in DKK, instead of EUR. This is usefull for stores primarily focused on Game Server monitization. But it would also be usefull for other creators as well.