Bug-7161 Open Library - Larger image, Read, borrow and checked-out status

To test:
1. go into system administration and search for "cover"
2. change "OpenLibraryCovers" to "add" and all other to "don't show"
3. verify that opac search results have small covers, while
   detail page has big ones

Signed-off-by: Dobrica Pavlinusic <dpavlin@rot13.org>
Addressing M. de Rooy's concerns

* remove console.log
* removed some comments that looked like debug code?
* remove ebook display -  I couldn't get it to work properly, and we want the bigger images. So it's gone.
* remove get_cover

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
June 27, 2012: Removing unused function keys from openlibrary.js.