title: daterangepicker trigger validation when I pick up a date
body: <p>I'm using jquery validation with daterangepicker. I have an issue when I try to choose a date. When I choose it for the first time, it doesn't show "Hello" but the second time it shows "Hello" and what I really want to do is validate this field when I click on button next. How can I do to avoid that "checkDate" being executed when I pick up a date in order to validate it when I click on button next?</p>
  
  <p>Here you can see my code:</p>
  
  <pre><code>$("#form_step1").validate({
      rules: {
          titulo: {
            required: true,
            maxlength: 300
          },
          reservationtime1:  {
            required: true,
            checkDate: true
          }
      },
      messages: {
          titulo: "At least 300 characters",
          reservationtime1: "You must pick up a valid date"
      },
      highlight: function(element) {
          $(element).closest('.form-group').addClass('has-error');
      },
      unhighlight: function(element) {
          $(element).closest('.form-group').removeClass('has-error');
      }    
  });  
  jQuery.validator.addMethod("checkDate", function(value, element) { 
  // My custom validation
  alert("Hello");
  });
  </code></pre>
  
  <p><a href="http://jsfiddle.net/B79z7/2/" rel="nofollow">http://jsfiddle.net/B79z7/2/</a></p>
  
  <p>Thanks</p>