title: Unable to run ipython-notebook 2.7 with jupyterhub
body: <p>I am trying to run ipython 2.7 notebooks with jupyterhub on Ubuntu 14.04 - but I haven't been able to figure out a way. Any suggestions?</p>
  
  <p>I know one needs to add kernels in the file ~/.ipython/kernels.json
  I have the following in this file:</p>
  
  <pre><code>{
   "argv": ["python3", "-m", "IPython.kernel",
            "-f", "{connection_file}"],
   "display_name": "Python 3",
   "language": "python"
  }
  {
   "argv": ["python2.7", "-m", "IPython.kernel",
        "-f", "{connection_file}"],
   "display_name": "Python 2",
   "language": "python"
  }   
  </code></pre>