Change API to Open Library Books

[Bruce]

Google Books requires API users to implement tons of watermarks, that don't really work with this application.

Solution:
Change the API to Open Library Books.
For this, the JSON must be parsed differently, due to another structure (obviously)

Task:

Change (and refactor) the scanning/downloading/parsing code so it works with the Open Library Books API.

Resources about the API can be found here.
We need to use the jscmd=details parameter, to get the description of the book.
We would query the book in ISBN:13

Sample request

[Damien Rivet]

Hi,

I'd love to work on migrating toward the Open Library API.

Edit: PR is now opened.