Default value for reminder_days_before in the DB doesn't match the code

In testing #336255: CCK datestamp fields totally broken and fields without timezone handling mostly broken and the new CCK date testsite install profile, I noticed a bug in signup.install. In signup_insert_default_signup_info(), reminder_days_before is set to 0, whereas the rest of the code treats this as if it defaults to 1. So, the DB doesn't match the reality you see when you visit admin/settings/signup unless you save that page. This means that all the signup-enabled nodes created by the install profile are configured to send reminders 0 days in advance, which is a non-sensical setting that's normally not possible in the code.