title: Why is respond_with being removed from rails 4.2 into it's own gem?
body: <p>In <a href="http://weblog.rubyonrails.org/2014/8/20/Rails-4-2-beta1/">rails 4.2</a> respond_with has been moved out of core into the responders gem.</p>
  
  <p>Beta release notes.</p>
  
  <p><code>respond_with has moved out and into its own proper home with the responders gem.</code></p>
  
  <p>Can someone please explain why? What makes the responders gem its proper home? What is wrong with it staying in the Rails gem?</p>