Added IP address as parameter to vhost class.

A VM I was creating couldn't start apache as I had one ssl-only vhost and the vhost template has the catch-all ("*") hard-coded. I've added ip_addr as a parameter so this can be specified if necessary, with the default of "*" to preserve the current behaviour. It's possibly a slightly bigger change than my previous pull requests on the nginx module so I won't be offended if I've not done it right!