Bug 11990 - Holds ratio report (circ/reserveratios.pl) sorts numeric values as text

Bug 11990 - Holds ratio report (circ/reserveratios.pl) sorts numeric values as text

This patch makes columns Holds, Items and "Hold ratio" to sort
numerically instead of lexicographically. Also changes default sorting
column from "Holds" to "Hold ratio" because this is a hold ratios
-report, not hold count report.

Also cleans up an excess aoColumn -definition, because aoColumns ==
aoColumnDefs without target operator. No point in defining columns
twice.

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>