get the card’s history
Make rspec default task when calling the rake command
Add Travis status
Merge branch 'master' into introducing_gemspec
adding rake and fixing deprecation issues:

 - rspec using double instead of mock: https://github.com/rspec/rspec-mocks/issues/153#issuecomment-12208638
 - rspec not_to raise exception with class:  https://github.com/rspec/rspec-expectations/issues/231