title: How to embed/mount existing Rails app into another Rails app?
body: <p>I have two Rails apps (using rails 3.0.7), call them "blog" and "auth". I'd like to mount "auth" from "blog" such that I can run the "blog" app and have certain requests routed to the "auth" app.</p>
  
  <p>It seems like I need to embed or perhaps create an "engine", but I'm not 100% sure which is correct.</p>
  
  <p>How can I embed the "auth" app inside of the "blog" app?</p>