[NFR] Phalcon\Http\Response can support send_file and getheader optimization?

[dreamsxin]

I display image, now:

            $filename = 'avatar.png';

            $etag = md5_file($filename);
            $this->response->setHeader('etag', $etag);
            $this->response->setHeader('Cache-Control', 'must-revalidate');

            $retag = $this->request->getHeader('HTTP_IF_NONE_MATCH');

            if ($retag AND $retag == $etag)
            {
                $this->response->setStatusCode(304, 'Not Modified');
                $this->response->send();

            } else {
                $this->response->setHeader('cache-control', 'max-age=3600');            
                $this->response->send();

                http_send_content_type("image/jpeg");
                http_send_file($filename);
            }

if has send_file:

            $filename = 'avatar.png';

            $etag = md5_file($filename);
            $this->response->setHeader('Etag', $etag);
            $this->response->setHeader('Cache-Control', 'must-revalidate');

            $retag = $this->request->getHeader('if-none-match');

            if ($retag AND $retag == $etag)
            {
                $this->response->setStatusCode(304, 'Not Modified');
                $this->response->send();

            } else {
                $this->response->setHeader('Cache-Control', 'max-age=3600');            
                $this->response->send_file($filename);
                $this->response->send();
            }

[phalcon]

This is already implemented but needs to be documented