Remove the need to reboot to rename ifaces
Remove the need to reboot to rename ifaces

`ip link set` can even set iface names. Let's do that, but keep the changes to the udev config so it will stick if/when the server reboots.

Also made sure we were using braces to delimit var names, just in case. And probably fixed `-n` usage against ext_ifaces, too.
nanobox-io/bootstrap