Improve Rails.env

Hi

In this commit http://github.com/rails/rails/co..., you (Pratik), insert a serie of shortcuts for RAILS_* constants.

Well, I like this change, but I think it can be improved to make something like this:

Rails.env # => "production"
Rails.env.production? # => true
Rails.env.development? # => false

This can be achieved adding a few lines to the Rails.env method:

  def self.env
    env = RAILS_ENV
    def env.production? # Or method_missing
      self == "production"
    end
    def env.development?
      self == "development"
    end
    def env.test?
      self == "test"
    end
  end
  env # returns the RAILS_ENV string
end

May be a "method_missing" could ba a better solution, but this is only an example.