Bug 16573: Define virtualshelves.created_on as datetime for existing installs

Bug 16573: Define virtualshelves.created_on as datetime for existing installs

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit 44785935bd45291a2ae36a5c9ab65b1e6cf69c5b)
Signed-off-by: Frédéric Demians <f.demians@tamil.fr>
(cherry picked from commit d2b20b2a82ef73423ec6571967173083ba333501)
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>