Add a new module, mod_ratelimit, which can rate limit the outgoing bandwidth

to a client.

This module was originally written at Joost by Sander Striker, Justin 
Erenkrantz, and myself.  We have been given permission by our employer to 
contribute this module.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@721965 13f79535-47bb-0310-9956-ffa450edef68