Google books site-plugin

Learning more about git by the minute - I now know how to branch properly :)

After seeing how relatively simple the iblist plugin was, I created a site-plugin for Google Books based on the google books API that you can consider to include. I also fixed a couple of https-bugs in snoopy since G-Books does not work without SSL... in case you do not want to include my site-plugin, you can consider just cherrypicking commit 05e37af6e94f6816a6efd19dc60fcb423f7265b7 for the SSL-fixes...