Allow running serve out-of-cluster

[robertgzr]

• kubeconfig can be passed via flag
• nicer logging
• using context instead of chan struct{}

Todo:

Debug TypeAssertionError in onAdd, onUpdate and onDelete ✅

t=2017-07-20T15:24:16+0000 lvl=eror msg="unable to assert type" func=onAdd want= got=
t=2017-07-20T15:24:16+0000 lvl=eror msg="unable to assert type" func=onAdd want= got=
t=2017-07-20T15:24:16+0000 lvl=eror msg="unable to assert type" func=onAdd want= got=
ERROR: logging before flag.Parse: E0720 15:24:17.215699   16917 reflector.go:363] github.com/kinvolk/cgnet/kube/pods.go:61: expected type *v1.Pod, but watch event object had type *v1.Pod
ERROR: logging before flag.Parse: E0720 15:24:18.222761   16917 reflector.go:363] github.com/kinvolk/cgnet/kube/pods.go:61: expected type *v1.Pod, but watch event object had type *v1.Pod

As suspected the problem was the wrong use of k8s.io/api/v1 instead of k8s.io/client-go/pkg/api/v1

Closes #9

[asymmetric]

Do you need this? It's gonna be called anyway as part of defer.

[robertgzr]

You're right 👍