bug 2047: adding icons to authorized values

bug 2047: adding icons to authorized values

This patch adds the ability to associate icon images with authorized values.
They're not displayed anywhere yet, though. There's also a database update
in here. I took version "3.00.00.075", but I can change that later if it gets
taken before I commit these patches.

DOCUMENTATION CHANGES: When you add or edit authorized values, you can now
associate image icons with them. These icons come from the same icon sets
that you can have with your itemtypes, such as media type. They don't show
up anywhere yet, but that's coming. Keep an eye on
http://bugs.koha.org/cgi-bin/bugzilla/show_bug.cgi?id=2047
for more updates.

Signed-off-by: Joshua Ferraro <jmf@liblime.com>