Move /usr/local/etc/rc to /etc/rc.opnsense in order to be able
to boot without /usr mounted. Move the /boot files along with
it since they require the same type of /usr/local-escapting.
1. This needs further testing. :)
2. Inspect rc script for commands depend on /usr tools
Our rc.shutdown stays where it is, if we can shutdown we should be
able to access it. If not, it's not grabbed via /etc/rc.shutdown.
