title: Laravel date validation failing to require 4 digit year
body: <p>I'm kind of puzzled at the results I'm getting from a Laravel date validation.  The rule in question is:</p>
  
  <pre><code>'date_of_birth'=&gt;array('required', 'date_format:n/j/Y')
  </code></pre>
  
  <p>What I'm finding is that if somebody enters 10/12/13, it passes validation, and gets stored as 10/12/0013.  Obviously, that's not good.  Is there any way of getting validation to demand a four-digit year?  I assumed that's what the Y in the format would do.</p>