Another album configuration option: merch download only

As an extension of the free download only option for albums, we’ve added “Merch download only” as an additional configuration option. What that means is that this album will ONLY be available as a free download with purchase of a merch item. Users cannot buy it OR claim it for free.

Additionally we’ve added a new field to the merch create form! If you pick album, you’ll be asked to include a download or say “this item doesn’t include a download”.