Create device-flashable images

This would be a very long-term enhancement that provides flashable images for popular devices like the Raspberry Pi, similar to MotionEyeOS. Ideally this would be based on BuildRoot or Yocto, and would likely want the following issues addressed as a prerequisite:

https://github.com/scottlamb/moonfire-nvr/issues/27
https://github.com/scottlamb/moonfire-nvr/issues/35
https://github.com/scottlamb/moonfire-nvr/issues/133
https://github.com/scottlamb/moonfire-nvr/issues/160

scottlamb / moonfire-nvr

Create device-flashable images #248