Networking configuration in kickstart templates

extracted from https://github.com/theforeman/foreman/pull/1565
Have you looked into using [network](https://fedoraproject.org/wiki/Anaconda/Kickstart#network)?
> Additional devices configured in kickstart with network command can be activated in installer using --activate option (since F16).

If it could be set up by anaconda, that would remove the need for a restart altogether. It would also make it possible to use the extra interfaces with other anaconda statements, such as ```repo``` and ```packages```.

Of course, older distro support might be tricky but the fewer we do in %post, the better IMHO.