Bug 9078 - is_holiday should honour holiday exceptions

Bug 9078 - is_holiday should honour holiday exceptions

Make is_holiday return 0 for holiday exceptions.

Note: This patch makes several current ok tests fail. My first guess is test data is not
constructed ok. More on this later.

Sponsored-by: Universidad Nacional de Córdoba
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Passed-QA-by: Paul Poulain <paul.poulain@biblibre.com>
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>