v0.4.0

This release has backwards incompatible changes so please read carefully.

The configuration key for firmware signing keys has changed from :public_keys
to :fwup_public_keys.

If you are not using nerves-hub.org for your NervesHub server, the configuration
keys for specifying the device endpoint for the server have changed. Look for
:device_api_host and :device_api_port in the documentation and example for
setting these.

• Enhancements
  • All firmware metadata is now passed up to the NervesHub. This will make it
    possible for the server to make decisions on firmware that has been loaded
    outside of NervesHub or old firmware that has been unloaded from NervesHub.
  • Code cleanup and refactoring throughout. More passes are planned.