v0.4.0

Locksmith now uses github.com/coreos/etcd/client, instead of the deprecated
github.com/coreos/go-etcd.

Locksmith now uses github.com/coreos/pkg/capnslog for logging.

The reboot strategy best-effort is deprecated, and locksmithd will complain
loudly if it is used. Please use an explicit reboot or etcd-lock strategy
instead.

Locksmith logs some information about the configured reboot window.

Locksmith supports etcd basic auth.

Locksmith again requires update-engine.service, and will start after
user-config.target system-config.target are reached.