title: How to center CardHeader title in Material-UI?
body: <p>How can I place title center on CardHeader (Material-UI)?</p>
  
  <p>I am using Material-UI v0.18.7</p>
  
  <p>Here is my code. I tried with textAlign: 'center' to titleStyle prop but that doesn't work.</p>
  
  <pre><code>const myTheme = {
     cardHeaderStylePref:{
        background: 'linear-gradient(to right bottom, #430089, #82ffa1)',
        color: config.actualWhite,
        height: 30,
        padding: 0
      }
  }
  &lt;Card&gt;
       &lt;CardHeader
              title={this.props.prefName}
              style={myTheme.cardHeaderStylePref}
              subtitleColor={myTheme.color}
              titleColor={myTheme.color}
              titleStyle={{textAlign: 'center'}}
        &gt;
        &lt;/CardHeader&gt;
        &lt;CardText&gt;
              Sample text
        &lt;/CardText&gt;
    &lt;/Card&gt;
  </code></pre>