Convert specs to RSpec 3.0.0 syntax with Transpec

This conversion is done by Transpec 2.2.4 with the following command:
    transpec

* 2 conversions
    from: obj.stub(:message)
      to: allow(obj).to receive(:message)

* 1 conversion
    from: obj.should_receive(:message)
      to: expect(obj).to receive(:message)

For more details: https://github.com/yujinakayama/transpec#supported-conversions