v0.13.2

Support Nerves Heart v2.0.0 attributes and features. Nerves Heart v2.0.0 is a
major update that addresses rare cases where devices would fail to reboot or
detect an issue. It also adds helpful statistics. See the docs for details.
Nerves Heart v1.x versions are still supported.

• Changes
  • Support guarded reboot and poweroff if Nerves Heart 2.0 is available.
    Reboots and poweroffs still gracefully stop the VM, but they now don't
    require Busybox reboot or poweroff, and they stop petting the hardware
    watchdog to set a hard limit.
  • Support Nerves Heart initialization completion notifications. This lets you
    protect the time between boot and :heart.set_callback/1 should something
    happen that prevents the callback from being set. This addresses an issue
    where the VM would think everything is great since it wasn't calling the
    callback to find out that it was not.