Bug 19511: Local cover images not centered in table column in staff client search...

Bug 19511: Local cover images not centered in table column in staff client search results

This patch modifies the JavaScript which embeds local cover images in
staff client catalog search results. It now adds the "thumbail" class to
the image, matching Amazon cover images.

To test you should have one or more titles with local cover images
attached. Apply the patch and clear your browser cache if necessary.

Enable both the AmazonCoverImages and LocalCoverImages system
preferences and perform a search which will return titles with local
cover images. Confirm that local covers are styled like Amazon covers.

Tested and confirmed local cover images are appearing quite nicely now.
Signed-off-by: Dilan Johnpullé <dilan@calyx.net.au>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>