Bug 16971: Missing dependency for HTML::Entities

Bug 16971: Missing dependency for HTML::Entities

This module is already used in opac-password-recovery.pl.
It is loaded in Acquisition, but not used (anymore?).
It is not yet listed in PerlDependencies.

Note: The module is packaged for Debian Wheezy and Jessie.

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: Brendan Gallagher <brendan@bywatersolutions.com>
(cherry picked from commit 92626f55c88661d1e5b8dea57bdca412df004123)
Signed-off-by: Frédéric Demians <f.demians@tamil.fr>