Bug 21824: Add ability to format dates in various formats in templates

Bug 21824: Add ability to format dates in various formats in templates

This patch adds the ability to set a date format for the Template Toolkit filter KohaDates

Test plan:
1) Apply this patch
2) In a template, use the filter param "dateformat => 'iso'"
3) Note the output is in ISO format

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Bouzid Fergani <bouzid.fergani@inlibro.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>