Bug 12666 - Fix poor HTML from circ/offline.tt

Bug 12666 - Fix poor HTML from circ/offline.tt

In koha-tmpl/intranet-tmpl/prog/en/modules/circ/offline.tt
- Cleaned up the HTML's missing </div>'s
- Corrected the autobuffer attribute to the newer preload one
- Added &nbsp; into empty title, since it will get replaced

TEST PLAN
---------
1) Run the circ/offline.pl page source through an HTML validator
   -- should get a few warnings
2) Apply patch
3) Recheck page source (confirm your page isn't cached!)
   -- should be clean

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Improves HTML validity, no regressions found.

Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>