R1:e8a7d8a905de

Provide software protections for HTTP response splitting

Summary:
This addresses a few things:

- Provide a software HTTP response spliting guard as an extra layer of
security, see http://news.php.net/php.internals/57655 and who knows what HPHP/i
does.
- Cleans up webroot/index.php a little bit, I want to get that file under
control eventually.
- Eventually I want to collect bytes in/out metrics and this allows us to do
that easily.
- We may eventually want to write to a socket or do something…