Convert specs to RSpec 2.14.8 syntax with Transpec

This conversion is done by Transpec 2.3.1 with the following command:
    transpec --keep its

* 362 conversions
    from: obj.should
      to: expect(obj).to

* 1 conversion
    from: obj.should_not
      to: expect(obj).not_to

For more details: https://github.com/yujinakayama/transpec#supported-conversions