v0.4.0

Changed how configuration works.

Grizzly now requires the serial port to be configured:

config :grizzly,
  serial_port: "/dev/ttyACM0"

Also added the pidof_bin configuration option to allow official
Nerves systems to work with some of the Grizzly scripts the call
that utility by using the busybox package and
pointing to the executable of pidof that is compiled with busybox.

If you are using a custom system you can add that utility to the
busybox config, and not need to use this configuration option.

config :grizzly,
  pidof_bin: "/srv/erlang/lib/busybox-0.1.2/priv/bin/pidof"

Double-check the version of busybox you are using and make sure that
version matches the version in the pidof_bin path.

Changed run_grizzly_bin to run_zipgateway_bin.