Add transpec as a dev dependency
Convert specs to RSpec 2.14.7 syntax with Transpec

This conversion is done by Transpec 2.0.0 with the following command:
    transpec

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

* 61 conversions
    from: == expected
      to: eq(expected)

* 2 conversions
    from: lambda { }.should
      to: expect { }.to

See also: https://github.com/yujinakayama/transpec#supported-conversions