title: Allow braces for blocks that return
body: <p>When I write a multi-line block that returns a value, I like to use braces instead of <code>do</code>-<code>end</code> in order to make evident that the purpose of the block is to return things, as opposed to do things. </p>
  
  <p>The standard configuration of Rubocop doesn't allow that, and <code>rubocop -a</code> converts any multi-line block in a <code>do</code>-<code>end</code> block.</p>
  
  <pre class="lang-rb prettyprint-override"><code># I like but Rubocop hates.
  expect {
    delete :destroy, id: thing.to_param
  }.to change(Thing, :count).by(-1)
  
  # I don't like but Rubocop does.
  expect do
    delete :destroy, id: thing.to_param
  end.to change(Thing, :count).by(-1)
  
  # That, we both like.
  before do
    stub_api_calls
    admin_sign_in create(:super_admin)   
  end
  </code></pre>
  
  <p>Is there any configuration parameter in Rubocop that allows this distinction?</p>
  
  <p>Edit: Or, at least, that avoids changing the brackets block if there is a dot (.) after the closing bracket. </p>