Upgraded your code to work with Ruby 2.1.1

As a newbie, I used your well written tutorial to learn about Guard and rspec working together. I made some changes to your code as follows, and decided to give back.
1. Added color output to Guard log.
2. Changed rspec code from should to expect to remove depreciation warnings.
3. Changed rspec_opts to progress, as nested seems to give errors.

Thanks for well written article.