Fixes #5207: Rudder init should check the validity of answers

I know this isn't strictly related, but since we're removing stuff, I feel we should remove the "sample data" question too. The sample data is WAY out of date, and recently actually caused a bug for a user. There is no need for this data at the moment, and it makes us look a bit like a "toy" application (ie, not very serious).

What do you think? We could easily include this in the same PR.