ISBN lookup

Solution for [isbn barcode lookup](https://duckduckhack.uservoice.com/forums/5168-ideas-for-duckduckgo-instant-answer-plugins/suggestions/3993476-isbn-barcode-lookup), written after I found myself needing such a feature. Uses the [Open Library](http://openlibrary.org) API.

Example queries:
* isbn 978-0-393-31604-9
* ISBN 0 486 20167 8
* isbn 1567312667

Note: To format ISBN numbers, this Spice includes the [isbnjs](code.google.com/p/isbnjs/) library, licensed under the MIT license. It also includes rather outdated information (from 2009) about ISBN group ranges; I can't use the provided script to update it since the link it uses seems to have gone dead. However, the worst that this can do is not put dashes into the ISBN.