title: Using implicit `subject` with `expect` in RSpec-2.11
body: <p>With the new <code>expect</code> syntax in rspec-2.11, how is it possible to use the implicit <code>subject</code>? Is there a better way than explicitly referencing <code>subject</code>, like below?</p>
  
  <pre><code>describe User do
    it 'is valid' do
      expect(subject).to be_valid    # &lt;&lt;&lt; can `subject` be implicit?
    end
  end
  </code></pre>