Jupyter nbextensions does not appear : <p>I tried to install jupyter_contrib_nbextensions : <a href="http://jupyter-contrib-nbextensions.readthedocs.io/en/latest/install.html" rel="noreferrer">http://jupyter-contrib-nbextensions.readthedocs.io/en/latest/install.html</a></p>

<p>Everything worked fine but when I open a notebook nothing changes. I can't see the new tool bar that I'm supposed to see. </p>

<p>When I reinstall the Extension, the process is the same (I don't have a message tellign me that the files already exists). I don't have an error. So I can't figure out why it doesn't work. </p>

<p>Thanks a lot.</p>
