title: presentViewController with unwind/dismiss view controller animation
body: <p>Currently my storyboard is as follows:</p>
  
  <p>Welcome->Login->Main</p>
  
  <p>Login is displayed using the default cover vertical transition.
  Instead of presenting Main the same way I would like to use the dismiss transition.</p>
  
  <p>How can I go about doing this?</p>