Bug 20507: Shelf browser does not update image sources when paging

Bug 20507: Shelf browser does not update image sources when paging

This patch updates the shelfbrowser include so that the system
preference check for Coce will function correctly.

To test, apply the patch and test the OPAC shelf browser with each of
the enhanced content options enabled: Coce, Amazon, Google. In each
case, page through the shelf browser to confirm that covers load
correctly.

Signed-off-by: Cab Vinton <bibliwho@gmail.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>