title: jquery , validator invalid class being applied to non-empty fields on submit
body: <p>I have a form where i am using jquery and validate. 
  I am using errorPlacement in the validate to put a border around required fields that are missing.
  it seems to work as i would like except when the fields are pre-filled.
  When the form is submitted, The validate marks the pre-filled text fields are invalid. 
  if I give focus and then leave the field the pre-filled fields will all remove the borders.
  See example at <a href="http://jsfiddle.net/paries/u3Td3/8/" rel="nofollow">http://jsfiddle.net/paries/u3Td3/8/</a></p>