script/runner for Rails 3.0.0.rc2

Since the otherwise most-excellent whenever plugin still generates the pre-Rails3-style script/runner command-lines (and since I don't have the time to go ahead and fix whenever), here's a version of script/runner that will work with the just released Rails 3.0.0.rc2, based on the original work of Philippe Creux.

#!/usr/bin/env ruby
# script/runner for rails 3.0.0.rc2

APP_PATH = File.expand_path('../../config/application',  __FILE__)
require File.expand_path('../../config/boot',  __FILE__)
require 'rails/commands/runner'