Bug 18985 - SQL reports 'Last edit' and 'Last run' columns sort alphabetically, not...

Bug 18985 - SQL reports 'Last edit' and 'Last run' columns sort alphabetically, not chronologically

This patch alters the DataTables configuration of the SQL reports list
so that date columns are identified via class rather than position.

To test, apply the patch and go to Reports -> Use saved.

Test the re-ordering of the creation date, last edit, and last run
columns. Each should sort correctly based on the date.

Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>