title: ReactJS Material-UI: Accept only positive unsigned integer values in TextField
body: <p>I have the following input field, I would like it to accept only positive integers, without giving the possibility to insert the characters <code>- + , .</code>.</p>
  
  <pre><code>&lt;TextField
    fullWidth
    type="number"
    placeholder={'[1-100]'}
    id="simple-start-adornmhent"
    onChange={this.handleChangeField('amount')}
    InputProps={{ inputProps: { min: 1 } }}
  /&gt;
  </code></pre>
  
  <p>Can you give me some advice?</p>