A patch is enclosed to support partial HTTP requests in roundup_server.

cgi/client.py already features explicit byte range support, thanks to an
HTTP_RANGE environment variable.  Presumably this works under mod_python
or WSGI, but roundup_server doesn't yet pass along the header value.

With this patch, my copy of roundup_server (behind an Apache 2.2 reverse
proxy) now successfully serves audio/video attachments to iOS clients.