Minimal custom userspace

[neuschaefer]

I'd like to build something like this with buildroot:

• Simple httpd serving a simple page with usage instructions
• Interaction mainly via ssh
  • user bmc for day-to-day BMC tasks (power on/off, SoL, etc.)
  • user sol to enable ssh sol@1.2.3.4 as a quick way to start a serial-over-LAN session
  • persistent storage for SSH pubkeys and other bits of configuration
• VNC (connected to video capture and USB input emulation) listening on localhost; forwarding via ssh -L ... → VCD/GFXI driver (V4L2) #4
• some sort of virtual media service, qemu-nbd → USB device mode driver #6
• version information
• update mechanism
• run shellcheck on all shell scripts