v0.6.0

This release makes a backwards incompatible API change that affects
how fwup public keys are shared with other projects. This should
only affect the nerves_hub library and should be handled by mix dependency
constraints.

• Backwards incompatible changes

  • The API to share fwup public keys has changed. This should only affect the
    nerves_hub library and should be handled by mix dependency constraints.
  • mix nerves_hub.ca_certificate create is now register. (It never created
    a certificate.

• Enhancements

  • Show API endpoint when running commands - this makes it more obvious when
    you're running against api.nerves-hub.org vs. your own instance