Simplify infoContent singular or plural strings

[sandersantema]

Alternatively it could also be simplified to:

infoContent.append("\(artists.count) Artist" + (artists.count > 1 ? "s" : ""))

[sandersantema]

I just discovered that this code is repeated in Artist.swift as well, I suppose it might be better to apply this change to all the files which share this code and possibly even better to abstract all the things Genre.swift, Artist.swift and possibly others share to a class or struct but that would require more swift knowledge which I currently don't have.

[BLeeEZ]

Cool, but a small change is required. If the count is zero no info should be appended to infoContent.