Fix monit monitoring for apache

Add a status vhost to apache, so that monit's http monitoring will work.
It doesn't particularly matter to the monit check what this vhost does
as long as it returns 200, but I thought it would be nice to use
apache's builtin status functionality.  Ideas cribbed from [1].  It
might also be possible to use monit's apache-status functionality to
alert on more sophisticated criteria, but this will do for now.

Open question: does collectd support apache-status? Might it also be
interested in this vhost?

Fixes #299.

[1] http://mmonit.com/wiki/Monit/MonitorApacheStatus