Removed Content-Transfer-Encoding from the list of default download h…

…eaders

`Content-Transfer-Encoding` is not a valid HTTP header (cf [RFC 7230, section 3.3.1](http://tools.ietf.org/html/rfc7230#section-3.3.1), [RFC 7231, section 8.3](http://tools.ietf.org/html/rfc7231#section-8.3), [IANA Message Header Registry](http://www.iana.org/assignments/message-headers/message-headers.xhtml)). The correct HTTP pendant would be `Transfer-Encoding: identity`, which were entirely bogus.

framework/web/Response.php

@@ -557,7 +557,6 @@ public function setDownloadHeaders($attachmentName, $mimeType = null, $inline =
             ->setDefault('Accept-Ranges', 'bytes')
             ->setDefault('Expires', '0')
             ->setDefault('Cache-Control', 'must-revalidate, post-check=0, pre-check=0')
-            ->setDefault('Content-Transfer-Encoding', 'binary')
             ->setDefault('Content-Disposition', "$disposition; filename=\"$attachmentName\"");
 
         if ($mimeType !== null) {