[Koha] upgrade script

I managed to put together an upgrade script today that will be going out with the 1.2.1 release. The upgrade script (koha.upgrade) will make backups of your koha data, and all of the koha scripts and html files before installing the new files and making any necessary changes to the database. The upgrade script also indicates changes that may need to be made to the Apache configuration. I suspect there aren't a whole pile of production Koha systems out there yet, apart from Katipo's clients and my schools. If you _are_ using Koha in a production environment, I'd really appreciate hearing from you before the 1.2.1 release goes out. Steve.