Rails Tutorial book upgraded to Rails 3.0.3 and RSpec 2.1.0

I've updated the Ruby on Rails Tutorial book to use the latest versions of Rails and RSpec—3.0.3 and 2.1.0, respectively. These are minor updates,* so there's no rush to upgrade if you don't want to, but I love keeping the book fully up-to-date. (If you do upgrade your system, make sure all your application test suites are still green. In particular, the book's sample application test suite should still pass.) Because of the minor nature of the changes, all the material in the Ruby on Rails Tutorial screencast series is still current as well.

*Actually, Rails 3.0.3 contains some important performance improvements via a major refactoring of the ARel SQL relational algebra library. The public API, on the other hand, is essentially unchanged, so most Rails developers will hardly notice any difference.