Add rakefile
Add TravisCI configuration
Transform settings tests into descriptor ones
Use descriptor on remaining tests

Conflicts:
	spec/use_cases/process_commit_spec.rb
	spec/use_cases/process_delete_commit_spec.rb
Fix failing test

Conflicts:
	spec/use_cases/process_commit_spec.rb
BUGFIX : calling private method
Fix rspec examples
BUGFIX : mistyped variable