idviews: Make description optional for the ID View object
Description of any object should not be required.
Part of: https://fedorahosted.org/freeipa/ticket/3979
Reviewed-By: Petr Viktorin <pviktori@redhat.com>
Reviewed-By: Petr Vobornik <pvoborni@redhat.com>
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>