iquik: fix some terrible bugs

- bi wasn't in the BSS, it wa pointing to 0 :-/
- env_dev_update_from_default can fail if we had no
  config (an that's okay) - we shouldn't bail out

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>
fw: update README and better path handling

Disallow things like :4/boot/vmlinux

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>