title: options "--read-only" Ipython Notebook
body: <p>I can't run my ipython notebook with the --read-only option.
  It says :</p>
  
  <pre><code>[NotebookApp] CRITICAL | Unrecognized flag: '--read-only'
  </code></pre>
  
  <p>It's weird because I've seen several blog mentionning it.
  I'm running with the 1.1 version of ipython.</p>
  
  <p>Do you know if this option was removed or moved elsewhere?</p>