Bug 11703 - Convert checkouts table to ajax datatable

When a patron has many checked out items, circulation.pl can take a very
long time to load ( on the order of minutes in some cases ). This is
primarily due to the processing of the previous checkouts list. If we
convert to this table to a datatable that fetches its data via ajax, we
can make circulation.pl far more responsive. The same should be done
with relative's checkouts as well.

Test Plan:
1) Apply this patch
2) Observe that the checkouts and relatives' checkouts tables
   are now loaded asynchronously
3) Observe and verify the renew and return actions are now
   ajax based and function in a manner equivilent to how they
   used to.

This bug had quite a few followups, so I squashed all of them into one
change so that code is easier to follow. Original commit messages are below:

Bug 11703 - Use the ajax datatables on patron details page

Bug 11703 - Convert holds tables to ajax datatables

Bug 11703 [QA Followup 1] - Center bProcessing message over table

Bug 11703 [QA Followup 2] - Remove icons from checkout and clear buttons

Bug 11703 [QA Followup 3] - Remove references to UseTablesortForCirc

Bug 11703 [QA Followup 4] - Add back in Today's checkouts/Previous checkouts rows

Bug 11703 [QA Followup 5]

Bug 11703 [QA Followup 6] - Move strings to an include file for translation purposes

Bug 11703 [QA Followup 7] - Fix issues spotted by koha-qa.pl

Bug 11703 [QA Followup 8] - Speed up api/checkouts.pl as much as possible

Bug 11703 [QA Followup 9] - Move scripts from api directory to svc directory

Bug 11703 [QA Followup 10] - Fix errors caused by rebase

Bug 11703 [QA Followup 11] - Prevent multiple fetchs from ajax source

Bug 11703 [QA Followup 12] - Fix problem detected by koha-qa.pl

Bug 11703 [QA Followup 13] - Removed uneccessary data from renewal box during renewal

Bug 11703 [QA Followup 14] - Fix table column span

Signed-off-by: Dobrica Pavlinusic <dpavlin@rot13.org>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Passes all tests and QA script.
Test plan on bug report:
http://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=11703#c98
Bug 11703 [QA Followup]

* Bold record title, fix table width
* Change output_pref_due to output_pref
* Retain functionality of IssuesDefaultSortOrder system preferences
* Use datatables.inc in circulation.tt
* Fix up holds table details
* Add plugin to about
* fix relatives' checkouts
* add too_many string
* remove dead syspref from db
* Sort relatives' checkouts and holds tables client side
* Provide context for translation of strings
* Fix unterminated string literal, add missing paren
* Add replacement of _AUTHOR_ with title's author for holds
* Format prices correctly
* Format checkout dates correctly

Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Bug 11703 [QA Followup] - Use format instead of replace for string translation
Bug 11703 [QA Followup] - Use interface instead of themelang for checkboxes plugin
Bug 11703 [QA Followup] - Restore showing earliest renewal date for 'too early' renewals
Added datatables