Improve rake task report on failure
Fix the exit status code returned by cucumber's rake task
Add tests to make sure cucumber's rake task doesn't output rake's backtrace and returns correct exit status code
Fix rake execution command: now it's called via "bundle exec"
Minor refactoring regarding code review
Rewrite the test with cucumber
Cleanup given Rakefile
Merge pull request #400 from avakarev/improve.rake.task.report.on.failure

Improve rake task report on failure