title: Image on Material UI CardMedia
body: <p>I´m having some troubles on getting an image from props on a CardMedia image:</p>
  
  <pre><code>&lt;Card className={classes.card}&gt;
      &lt;CardMedia 
          className={classes.img}
          image={this.props.recipe.thumbnail}
      /&gt;
      &lt;CardContent className={classes.content}&gt;
          &lt;Typography gutterBottom variant="headline" component="h2"&gt;
              {this.props.recipe.title}
          &lt;/Typography&gt;
          &lt;Typography component="p"&gt;
              {this.props.recipe.ingredients}
          &lt;/Typography&gt;
      &lt;/CardContent&gt;
      &lt;CardActions&gt;
          &lt;Button 
              href={this.props.recipe.href}
              Recipe
          &lt;/Button&gt; 
      &lt;/CardActions&gt;
  &lt;/Card&gt;
  </code></pre>
  
  <p>It just doesnt render at all the images; all the other props values are rendered as they has to.
  Also as Material UI I had specified the CardMedia height on a JS css.</p>
  
  <p>Does anyone knows why this happens?</p>