Bug 1633: [SIGNED-OFF] Add support for uploading images to Koha

Bug 1633: [SIGNED-OFF] Add support for uploading images to Koha

A frequently-requested feature for Koha, especially by special libraries, is
the ability to upload local cover images into Koha.

This patch adds a bibliocoverimage table, and image handling code in the
C4::Images module. Key features of the implementation include:
1. The ability to have multiple cover images for a biblio
2. Handling for "full size" (800x600) and thumbnail-size (200x140) images
3. Uploading images directly from the record view

The image display functionality by Koustubha Kale of Anant Corporation will
follow in a second patch.

Special thanks to Koustubha Kale and Anant Corporation for the initial
implementation of local cover images, and to Chris Nighswonger of Foundation
Bible College for his prior work on patron images.

Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>
Signed-off-by: Magnus Enger <magnus@enger.priv.no>
Will add comments on Bugzilla.

Patch failed to apply because installer/data/mysql/sysprefs.sql had changed in master.
Corrected the same with this new patch.