Expose $VOPONO_NS_IP environment variable to the PostUp and PreDown scripts, and the application to run

[d4h0]

This looked easy to implement, so I thought I just implement it myself.

VOPONO_NS_IP is exposed to the application to run because this might be useful for configuring it (e.g. for the transmission-daemon that is mentioned in the user guide).

Please feel free to edit/remove any of my additions to the user guide however you like (English isn't my native language, in case that isn't clear by now... ;)).

I don't really know much about networking, and I'm not 100% sure that everything I wrote is correct (especially, that the network namespace IP isn't reachable from other machines in the local network).

Please let me know if you think there is anything that might be wrong.

[jamesmcm]

Thanks, this is really useful!

It might also be helpful to expose the IP of the host machine from the network namespace too, for doing this the other way around - e.g. a service running on the host that only be connected to via the network namespace.