update rspec
Convert specs to RSpec 3.1.7 syntax with Transpec

This conversion is done by Transpec 2.3.8 with the following command:
    transpec

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

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

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

* 15 conversions
    from: obj.should_not
      to: expect(obj).not_to

* 3 conversions
    from: lambda { }.should_not
      to: expect { }.not_to

* 2 conversions
    from: < expected
      to: be < expected

* 2 conversions
    from: > expected
      to: be > expected

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