title: Failed to upgrade plotly using pip
body: <p>I'm trying to upgrade plotly which is right now at 2.0.7 and mine is 1.3
  using the following:</p>
  <pre><code>pip install plotly --upgrade
  </code></pre>
  <p>But I'm having this error:</p>
  <pre><code>Installing collected packages:
   Found existing installation: plotly 1.3.1
  Cannot uninstall 'plotly'. It is a distutils installed project and thus we cannot accurately determine which files belong to it which would lead to only a partial uninstall.
  </code></pre>