title: File upload mime-type validation with Laravel 4
body: <p>When I upload a well-formed MP3 file, Laravel 4 tells me it's not <code>audio/mp3</code> but <code>application/octet-stream</code>, which makes this validation fails:</p>
  
  <pre><code>$validator = Validator::make(
      array('trackfile' =&gt; Input::file('trackfile')), 
      array('trackfile' =&gt; 'required|mimes:mp3')
  );
  
  if($validator-&gt;fails())
      return 'doesn\'t works because mime type is '.Input::file('trackfile')-&gt;getMimeType();
  else
      return 'it works!';
  </code></pre>
  
  <p>Why doesn't it upload the file as an <code>audio/mp3</code> file ?</p>
  
  <p>(I already added <code>'files' =&gt; true</code> to the form declaration)</p>