Does not work with Rails 3

There is a detection to see if the rails app is rack based, which is too naive.

In lib/rack/adapter/rails.rb:

  def rack_based?
    rails_version = ::Rails::VERSION
    rails_version::MAJOR >= 2 && rails_version::MINOR >= 2 && rails_version::TINY >= 3
  end

In rails 2.3.8 (for example), we get true && true && true.

In rails 3.0.0, we get true && false && false, which means it thinks the rails isn't rack based.

Could we check for a config.ru in rails root instead?

Or maybe, if we detect rails 3, skip all the rails stuff, and just treat it like a rack app.