Add keepalive_request, hostname_lookups, start_servers, server_limit, max_clients, max_request_per_child to the template and class

Hi,

I've keepalive_request, hostname_lookups, start_servers, server_limit, max_clients, max_request_per_child to the template and class.

Endeed, I think we must use more tunning directive in this puppet module to configure apache. This directivres are writed with defaults values.

++

they could be httpd defaults, but those are mpm dependent…
I'd leave it them `undef`. perhaps have a flag for tuning based on CPU/RAM.
Though that's hard.