title: how to clear error when using jquery validate and custom errorPlacement
body: <p>I am using jquery and validate to validate my form.
  Instead of adding an element to the missing field I am adding a border to the element
  using this option errorPlacement</p>
  
  <pre><code>$("#signup-form").validate({
         submitHandler: function(form) {
        form.submit();
     },
     errorPlacement: function(error, element) {
        element.css("border", "solid 1px red");
     }                    
  });
  </code></pre>
  
  <p>the one thing i can not seem to figure out is how to clear it when valid?</p>
  
  <p>So I started with the above code. Then tried and i am confused with the results.
  If I do not have the <code>success:</code> option when a field fails it adds the class successfully. But as soon as I add the <code>success</code> option all the required fields are getting that class, and if I inspect the element I see <code>&lt;input class="required invalid valid"&gt;</code> so I am doing something incorrectly.</p>
  
  <pre><code>           $("#signup-form").validate({
                  submitHandler: function(form) {
                      // do other stuff for a valid form
                      //form.submit();
                  },
                  errorPlacement: function(error, element) {
                      element.addClass("invalid");
                  },        
                  success: function(error) {
                      // change CSS on your element(s) back to normal
                  },                    
                   debug:true
              });
  </code></pre>