Upgrade to Rails 3.0.6

I've just upgraded the Ruby on Rails Tutorial to use Rails 3.0.6, which contains an important security fix (though not one that affects the Rails Tutorial sample application). Upgrading your applications is easy: just edit your Gemfile and change the Rails gem version from '3.0.5' to '3.0.6'. Then run

$ bundle update rails && bundle install

to apply the update.