Bug 28178: Display the correct image in the image viewer

Bug 28178: Display the correct image in the image viewer

When there are several images attached to a bibliographic record, one can click
an image and see it in the image viewer. But the first image is always displayed.

Test plan:
0. Turn on LocalCoverImages and AllowMultipleCovers
1. Attach at least two images to a bibliographic record
2. Go to the detail page, click the "Images" tab and click the second
image.
=> With this patch applied you should see the image you selected

Sponsored-by: Gerhard Sondermann Dialog e.K. (presseplus.de, presseshop.at, presseshop.ch)
Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>