Tuan M. Hoang authored May 21, 2018 and Carlo Landmeter committed May 24, 2018

This commit allows starting 'firstboot' service (see aports/openrc),
which will setup installation through SSH if specified in kernel
parameters.

Real wget is used instead since busybox's wget is broken without
openssl binary #8917. Credits to clandmeter.

- Allow adding DNS server in configure_ip()
- Prefix kernel parameters with KOPT_