railstutorial/sample_app_2nd_ed — pull request #23 by postscripter (2013-01-21 22:53:05+00:00)
Title: Added system dependant gems for automated testing with Guard

From the book http://ruby.railstutorial.org/book/ruby-on-rails-tutorial#sec-guard
I thought it would be nice to add these three collection of system dependent gems mentioned in your book.