Translate Book.edition_info

[dato]

The Book.edition_info method—that ends in AltText for images when serializing to AP—doesn't seem to be translated (I'm referring to words like, say, Paperback, instead of Tapa blanda.

I guess it should be traduced to the UI language of the active user (since que don't quite know the language of the status).

One additional improvement: the edition language is included, but an exception is made for "English". Would be nice either not to include it at all; or include it without grandfathering; or do some guesswork based on status lang (which we don't know; could be added eventually I guess), or UI lang (which is not quite exact either).