Installation should allow droping existing DB

Updating the server packages usually triggers a schema update that takes VERY long to finish, in my case more than 24 hours. It would be very useful to have the option in install.php to drop the DB and restart from scratch. Within the time it takes to finish the schema update all alive clients will have reported again, so the DB is fully back in operation - except for the nodes that for some reason do not report any more, but I don't care much about these. Default should be not to drop the DB.