CapybaraRspecGrader

- allow testing student archive submissions for rails-intro HW2, but avoid starting up a rails server for each submission, we thought to try using Capybara or something similar.
- This runs tests similar to mechanize does for remote sites, and is a simple example of file changes when adding a grader.
- If there is a way of switching out the driver and reuse existing tests, that would be better, eg to Capybara.current_driver = :mechanize 
- might require copying files around for testing: spec_helper and Gemfiles.
- run test by hw/features/rails_intro_testing_feature which runs on the rails-intro/public/rottenpotatoes app with a specially added spec_helper...