title: Regular expression to validate valid time
body: <p>I need a regular expression to validate time.</p>
  <p>Valid values would be from <code>0:00</code> to <code>23:59</code>.</p>
  <p>When the time is less than <code>10:00</code> it should also support one character numbers.</p>
  <p>These are valid values:</p>
  <ul>
  <li><code>9:00</code></li>
  <li><code>09:00</code></li>
  </ul>