Convert specs to RSpec 3.0.2 syntax with Transpec

This conversion is done by Transpec 2.3.1 with the following command:
    transpec -f -c rake spec

* 22 conversions
    from: obj.should
      to: expect(obj).to

* 21 conversions
    from: it { should ... }
      to: it { is_expected.to ... }

* 18 conversions
    from: == expected
      to: eq(expected)

* 5 conversions
    from: it { should_not ... }
      to: it { is_expected.not_to ... }

* 2 conversions
    from: its(:attr) { }
      to: describe '#attr' do subject { super().attr }; it { } end

* 2 conversions
    from: obj.should_not
      to: expect(obj).not_to

* 2 conversions
    from: proc { }.should
      to: expect { }.to

* 1 conversion
    from: be_false
      to: be_falsey

* 1 conversion
    from: be_true
      to: be_truthy

For more details: https://github.com/yujinakayama/transpec#supported-conversions