system-docker network container: add iptables

[camrossi]

RancherOS Version: 0.7.0

**Where are you running RancherOS? BareMetal

As per #446 it should be possible to configure iptables at start up trough the network container.
However it seems only the console contains the iptables executable.

iptables should be added to the network container.

Thanks

[joshwget]

@SvenDowideit I think we need to add iptables to the base image. We currently bind mount it into the console from the host. I'm assuming it's done this way to save space, but I don't think it's a good idea to have a special case for just this one binary. It's not that big anyways.

[SvenDowideit]

I'd rather go the other way - but we'll see

[joshwget]

What other way? I'm not sure what you mean.

[SvenDowideit]

have less in the base image, and compose things together.

[joshwget]

I'd mostly prefer that too, but it's not possible with buildroot. We can revisit it in more depth after #1478 is merged.

[SvenDowideit]

this was added in v0.9.0 by #1669