title: Jupyter + rpy2 outputs to command prompt instead of notebook cell
body: <h3>Issue description</h3>
  
  <p>Whenever loading rpy2 in a Jupyter notebook, R code executed with a <code>%%R</code>cell magic gets printed in the command prompt instead of the notebook cell. Plots show up properly in the notebook though.</p>
  
  <p><a href="https://i.stack.imgur.com/ytZ5b.png" rel="noreferrer"><img src="https://i.stack.imgur.com/ytZ5b.png" alt="enter image description here"></a></p>
  
  <p>I also noticed that the <code>%R</code> inline magic works properly, with code printed in the cell as expected. </p>
  
  <h3>Installation steps</h3>
  
  <ol>
  <li>Python 2.7.11 :: Anaconda 2.5.0 (64-bit)  </li>
  <li>notebook 4.1.0 installed via pip</li>
  <li>R 3.3.1 (x64) located in Program Files  </li>
  <li><a href="http://www.lfd.uci.edu/~gohlke/pythonlibs/#rpy2" rel="noreferrer">rpy2-2.7.8-cp27-none-win_amd64.whl</a> installed via pip  </li>
  <li>PATH:  
  
  <ul>
  <li><code>R_USER = C:\Users\myusername</code>  </li>
  <li><code>R_HOME = C:\Program Files\R\R-3.3.1</code></li>
  <li>Added <code>C:\Program Files\R\R-3.3.1\bin\i386</code>  </li>
  </ul></li>
  </ol>