Bug 19356: Move staff client cart JavaScript to the footer

Bug 19356: Move staff client cart JavaScript to the footer

This patch modifies the staff client cart template so that
JavaScript is included in the footer instead of the header.

To test, apply the patch and test the JavaScript-driven features of the
cart: All button controls, DataTables functionality.

Signed-off-by: Aleisha Amohia <aleishaamohia@hotmail.com>
Correction for QA: Removed contditional around footer JS (from
copy-paste) because it will always be true.

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>