Add power-on/off profiles

This version adds a few new commands:

• power which allows a power profile (on, off, force-on, force-off, rescue) which
  will use the 0.06 feature of the firmware to run a small scriptlet to handle power via pins:

i.e.:
jumpstarter power rescue orin-nx-00
jumpstarter power off orin-nx-00

• set-config, which allows setting config parameters stored into the board.

• get-config, which allows gett config parameters from the board:

# jumpstarter get-config orin-nx-00
name: orin-nx-00
tags: orin-nx-00,orin,orin-nx,16gb
json:
usb_console:
power_on: p1,bL,w5,bZ
power_off: p1,bL,w5,bZ,w10,bL,w110,bZ
power_rescue: p1,bL,w1,bZ,w1,aL,rL,w1,rZ,w1,aZ