Extend vhost data collection to a mod_status summary report extention

[wrowe]

Given that mod_bmx_vhost doesn't present really human readable summaries, exposing the formatted results to a mod_status extension would be very useful to admins.

This would show up similar to the "SSL/TLS Session Cache Status:" block following the core mod_status results, e.g. http://www.apache.org/server-status - the mod_status now allows any module to plug in some 'extra text' at the bottom of the status report.

It costs the user resources to plug in mod_bmx_vhost tracking and collect the data. Providing them the results in multiple formats is not particularly an extra workload on the server.