Convert specs to RSpec 2.99.1 syntax with Transpec

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

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

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

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

* 4 conversions
    from: be_false
      to: be_falsey

* 4 conversions
    from: be_true
      to: be_truthy

* 2 conversions
    from: obj.stub(:message)
      to: allow(obj).to receive(:message)

* 1 conversion
    from: -> { }.should_not
      to: expect { }.not_to

* 1 conversion
    from: Klass.any_instance.should_receive(:message)
      to: expect_any_instance_of(Klass).to receive(:message)

* 1 conversion
    from: expect(collection).to have(n).items
      to: expect(collection.size).to eq(n)

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