NewController constructs a new Controller object and returns it.

Controller is the controller which, among other things: - loads configuration from disk - checkpoints configuration to disk - downloads new configuration from the API server - validates configuration - tracks the last-known-good configuration, and rolls-back to last-known-good when necessary For more information, see the proposal: https://github.com/kubernetes/community/blob/master/contributors/design-proposals/dynamic-kubelet-configuration.md.