Bug 28825: Can't edit local cover image for item from details page

Bug 28825: Can't edit local cover image for item from details page

This patch corrects the markup for local cover images attached to items.
The correction allows correct display of an "edit" link when the user
clicks an item's cover image and views it in the lightbox-style modal.

To test, apply the patch and make sure the "LocalCoverImages" system
preference is enabled.

- View the details of a bibliographic record in the catalog which has
  items attached..
- In the table of holdings, click Edit -> Upload image.
- Upload an image for the item and return to the bibliographic detail
  page.
- Your image should now be displayed in the holdings table.
- Click the image to view it.
- In the footer of the modal there is an edit link: "Local cover image
  (edit). Before this patch the edit link would lead to a missing page.
  After applying the patch the link should take you to the "Image view"
  where you have the option of deleting the image or uploading another
  one.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>