title: Validate p:calendar value to be not greater than today's date
body: <p>I am using the component  to allow the user pick the date they were born (Birth Date). I should display an error message if the user picks a day greater than today's date to prevent the age for been a negative number. My component looks like this:</p>
  
  <pre><code>&lt;p:calendar id="fechaNacimiento" yearRange="c-100:c"
      pattern="dd/MM/yyyy" navigator="true"
      value="#{afiliadoController.afiliado.fecha_nacimiento}"
      requiredMessage="Debe de insertar la fecha de nacimiento del Afiliado."
      showOn="button"
      readonly="#{facesContext.currentPhaseId.ordinal eq 6}"
      required="#{request.getParameter('validate')}"&gt;
  
  &lt;/p:calendar&gt;
  </code></pre>
  
  <p>I am using PrimeFaces and OmniFaces and JSF 2.2. I was trying to validate this by using <code>&lt;o:validateOrder components=""/&gt;</code> but I would need two component and I only have one. What other options do I have?</p>