Bug 1633: [SIGNED-OFF] Display local cover images

Bug 1633: [SIGNED-OFF] Display local cover images

This patch adds display of local cover images in the following places:
1. OPAC Results page
2. OPAC Details page
3. Separate image viewer page for the OPAC
4. Intranet Details page
5. Separate image viewer page for the Intranet

Display in the Details and (OPAC) Results pages is handled via Javascript
rather than via direct embedding, to better handle the situation where most
records have local cover images, but a few do not.

Local cover images do not currently display in the Intranet Results page

How to use/test :
Assign user permission to the user Tools > (upload_local_cover_images Upload
local cover images).  In order to upload local  images, login to the staff
client. Go to Home > Tools > Upload Cover Images. Here you can upload cover
images either singly or in bulk in the form of a zip file.  If uploading
singly, click on image file, browse the image from your local disk, type in
the biblio number of the catalogue entry and press upload.  If uploading in
bulk as a zip file, the zip file must contain (in addition to cover images)
one text file named either datalink.txt OR idlink.txt. This file should
have mapping of biblionumber to image file name in the zip one per line
with comma or tab as delimiters. For example:

1, scanned_cover_image_of_bib_no_1.jpg
2, scanned_cover_image_of_bib_no_1.jpg

Cover images will be resized to a large image of 800x600 and a thumbnail of
200x140. Depending on the setting of AllowMultipleCovers, it is possible to
upload multiple images for a single bibliographic record. However, even if
multiple covers are permitted, you have the option of replacing the existing
covers by checking the "Replace existing covers" option on the upload screen.

1. The patch adds a menu link in Tools from where you can upload local cover
   images
2. It adds a user permission to enable access control to this menu item under
   Tools
3. It adds a system preference OPACLocalCoverImages under Enhanced Content.
   This needs to be turned on to show local cover images in OPAC.

Once you have uploaded local images, if you search for the biblio, the local
cover should show up in search as well as search detail pages in the OPAC, and
the details view in the Intranet.

Koustubha Kale is working on another patch which will allow us to set a cover
image source priority in system preferences, and which will then gracefully
fail over to the next source if image is not available from the first choice
source.

Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>
Signed-off-by: Magnus Enger <magnus@enger.priv.no>
Signed-off-by: Koustubha Kale <kmkale@anantcorp.com>
Rebased the patch because it was failing with koha-tmpl/intranet-tmpl/prog/en/css/staff-global.css due to changes pushed in master.
Applies cleanly now.