Merge tag '0.2.0' into develop

0.2.0
Add cucumber task.
The default rake task is cucumber.
Merge pull request #8 from yasuhito/feature/rake_cucumber

Feature/rake cucumber
Add rake rubocop task.
Merge pull request #9 from yasuhito/feature/rake_rubocop

Add rake rubocop task.
Use reek.
Reword uncommunicative names (refs #3).
Merge pull request #10 from yasuhito/feature/reek

Feature/reek
Refactoring.
Merge pull request #11 from yasuhito/feature/reek

Refactoring.
Refactoring.
README -> README.md
Add Travis badge.
Add rake to bundle.
Add utf-8 encoding comments (ruby1.9).
Separate Bf class into lib/bf.rb.
Add codeclimate badge.
Add gemnasium badge.
Cleanup and update README.md