Retire the apache_ratelimited role

Retire the apache_ratelimited role

And introduce a rate_limit param to the apache2 class.  The
bugs_web role sets that option to true on inclusion, as does
the packages role.

The snapshot role had slightly different rate limiting in the
apache class.  This has now been removed in favor of rate limiting
in the snapshot_web class.

To enable this, all web traffic (even on not-ratelimited systems)
is sent to the http chain.  At the end, all traffic gets accepted
and services that want to interfere can do things before prio 90.