cubicweb-book #1290564 title of a book should not be required if the book is in OpenLibrary [validation pending]

As a user, I want to be able to input a book by only specifying and ISBN number, if that book is in OpenLibrary.

(this is currently not possible as the title is mandatory)

prioritynormal
typeenhancement
done in0.7.0
load0.200
load left0.000
closed by<not specified>