Send content-length for /favico.ico

Browser was stuck trying to download and server was reporting
connection timeout after a minute.

Author: rouilj

roundup/scripts/roundup_server.py

@@ -321,6 +321,7 @@ def inner_run_cgi(self):
 
             self.send_response(200)
             self.send_header('Content-Type', 'image/x-icon')
+            self.send_header('Content-Length', len(favico))
             self.end_headers()
 
             # this bufsize is completely arbitrary, I picked 4K because