[k8s 1.8] kubelet flag deprecations

[lblackstone]

Is this a BUG REPORT or FEATURE REQUEST?

BUG REPORT

For Kubernetes 1.8, the kubelet.service includes a couple deprecated flags that should be updated/removed.

Related to #1938 /cc @s-urbaniak

Flag --require-kubeconfig has been deprecated, You no longer need to use --require-kubeconfig. This will be removed in a future version. Providing --kubeconfig enables API server mode, omitting --kubeconfig enables standalone mode unless --require-kubeconfig=true is also set. In the latter case, the legacy default kubeconfig path will be used until --require-kubeconfig is removed.
Flag --minimum-container-ttl-duration has been deprecated, Use --eviction-hard or --eviction-soft instead. Will be removed in a future version.