Bug 19839: Removed Warning (invoice.pl - uncertainprices)

Bug 19839: Removed Warning (invoice.pl - uncertainprices)

Test Plan
[1.] Check the patch to see that I have removed:
$template->param( uncertainprices => 1 ); from line 204 as Mr Druart has instructed to do
(to get to the patch see the comment above by Mr Druart)

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
(cherry picked from commit db7e3a41b15829a11d9f4465c95e36c7fd3eb735)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>