Utilizing rc.local

[introt]

rc.local "is executed at the end of each multiuser runlevel", and does nothing by default. desertbot adds /sbin/iw wlan0 set power_save off to keep the wifi radio on, but we could also use it for runtime setup stuff like getting the ssh fingerprint && IP out etc. since it seems to be the easiest way to plug stuff in before first boot/prior to getting shell access.

Reminder to self: after you have ssh access, you can install Ansible; no need to reinvent the wheel.