variables in "include"

[Kaspars]

> the problem is that gives them a ton of control, and also if the file 
> is removed i think nginx will not be able to start. there is no 
> configuration macro to test the existence of a file and included it 
> conditionally.

The problem is that currently for every change in nginx.conf you have to 
restart the server. That's why something like:

/home/var/vhosts/*/nginx.config

doesn't make sense, as it requires a restart (or a silent re-read of the 
config file).