Install cupertino and transpec.

transpec could not run due to this error:

https://github.com/nomad/cupertino/issues/109

So I have to add it to Gemfile.
Convert specs to RSpec 3.0.3 syntax with Transpec

This conversion is done by Transpec 2.3.6 with the following command:
    bundle exec transpec

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

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

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

* 2 conversions
    from: it { should ... }
      to: it { is_expected.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

* 1 conversion
    from: be_true
      to: be_truthy

* 1 conversion
    from: obj.should_receive(:message)
      to: expect(obj).to receive(:message)

For more details: https://github.com/yujinakayama/transpec#supported-conversions
Update Sidekiq to 3.2.