Bug 27815: "Remove" in point of sale untranslatable

Bug 27815: "Remove" in point of sale untranslatable

This patch modifies the Point of Sale template so that the "Remove"
button can be translated. The string in the JavaScript block wasn't
wrapped in the correct function.

To test, apply the patch and test that the correct strings are
translatable. In this example I'm testing fr-FR:

- Update a translation:

  > cd misc/translator
  > perl translate update fr-FR

- Open the corresponding .po file for the strings pulled from
  the template: e.g. misc/translator/po/fr-FR-staff-prog.po
- Locate strings pulled from pos/pay.tt for translation to confirm the
  update, e.g.:

  #: koha-tmpl/intranet-tmpl/prog/en/modules/pos/pay.tt:189
  #, c-format
  msgid "Remove"
  msgstr "Enlever"

- Install the updated translation:

  > perl translate install fr-FR

- In the staff client, go to Point of Sale.
- Switch to the French translation and click the "Ajouter" button next
  to one of the items for purchase.
- In the "This sale" table, the item you added should have a
  corresponding "Enlever" button.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>