sfWebRequest returns file extension "bin" when uploading a pdf file with Firefox under Mac OS

added the missing mime-type

Works for me, when adding the correct extension:

<?php

  $types = unserialize(file_get_contents('mime_types.dat'));
  $types["application/x-pdf"] = "pdf";
  asort($types);
  file_put_contents('mime_types_new.dat', serialize($types));

(In [13386]) [1.0, 1.1, 1.2] added mime type for PDF (closes #4483)

(In [13387]) [1.1, 1.2] added mime type for PDF (closes #4483)