Fixed the CreationDate value format when creating PDFs.

This was confusing Adobe Reader and not allowing it to save PDFs.

This bug appears to have been introduced in commit 08fc50d149745b078c9fd73a213c8c83307beaa2 which was applying the patch from http://qt.gitorious.org/qt/qt/merge_requests/706 but missed two lines.

This should fix issue http://code.google.com/p/phantomjs/issues/detail?id=663 .