Bug 16270: Typo authentification/authentication

Bug 16270: Typo authentification/authentication

Test plan;
Trigger /cgi-bin/koha/errors/404.pl
Confirm the typo without the patch and that it's fixed with this patch
applied.

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit 1c85d476aa8604fb93f0c27bec207aa9f4048467)
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>