Fix for bug # 1008534 (Attachments with spaces being converted to  )

I don't believe this will have any other ramifications as I wouldn't expect filenames to contain HTML Entities.

src/download.php

@@ -108,7 +108,7 @@ if (is_object($message->header->disposition)) {
     $filename = $header->getParameter('name');
 }
 
-$filename = decodeHeader($filename,true,true);
+$filename = decodeHeader($filename,true,false);
 $filename = charset_encode($filename,$default_charset,false);
 
 // If name is not set, use subject of email