title: Reactstrap Progress not rendering
body: <p>I am trying to render a progress bar and a button using reactstrap@7.1.0. The button is rendered where as the progress bar is not rendered. What am i missing?
  Also bootstrap version is 4.2.1.</p>
  
  <pre><code>import React from 'react';
  import { Progress,Button } from 'reactstrap';
  
  const Home = (props) =&gt; {
    return (
      &lt;div&gt;
      &lt;Button color="danger"&gt;Danger!&lt;/Button&gt;
      &lt;div className="text-center"&gt;25%&lt;/div&gt;
      &lt;Progress value="25" /&gt;
      here i am 
  
  
    &lt;/div&gt;
    );
  };
  
  export default Home;
  </code></pre>
  
  <p>The following HTML code is rendered</p>
  
  <pre><code>&lt;div class="progress"&gt;
  &lt;div class="progress-bar" role="progressbar" aria-valuenow="0" aria-valuemin="0" aria-valuemax="100" style="width: 0%;"&gt;
  &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>