Convert specs to RSpec 3.1.5 syntax

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

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

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

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

* 8 conversions
    from: be_true
      to: be_truthy

* 5 conversions
    from: obj.should_receive(:message)
      to: expect(obj).to receive(:message)

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

* 2 conversions
    from: Klass.any_instance.stub(:message)
      to: allow_any_instance_of(Klass).to receive(:message)

* 2 conversions
    from: be_false
      to: be_falsey

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

* 1 conversion
    from: Klass.any_instance.should_receive(:message)
      to: expect_any_instance_of(Klass).to receive(:message)
Test against MRI 2.1.3