rspec-expectations: Better failure message when two unequal objects have the same string representation.

In the following error:

describe 'time' do
  it 'should be equal' do
    expect(Time.now).to eq(Time.now)
  end
end

> rspec repro.rb
F

Failures:

  1) time should be equal
     Failure/Error: expect(Time.now).to eq(Time.now)

       expected: 2013-10-02 19:51:58 -0700
            got: 2013-10-02 19:51:58 -0700

       (compared using ==)

       Diff:
     # ./repro.rb:3:in `block (2 levels) in <top (required)>'

Finished in 0.00273 seconds
1 example, 1 failure

Failed examples:

rspec ./repro.rb:2 # time should be equal

expected and actual are presented as the same, even though they’re not. While we do call out that == was used to compare them, this is still a confusing error. Better would be something like:

   expected: 2013-10-02 19:51:58 -0700 (Object ID 12345)
        got: 2013-10-02 19:51:58 -0700 (Object ID 56789)

Relevant code is https://github.com/rspec/rspec-expectations/blob/master/lib/rspec/matchers/built_in/eq.rb