kubectl logs -l will print logs for pods with the same label, however
it doesn't support pods with multi containers. This change adds support
to it with --all-containers.

Ussage:
$ kubectl logs my-pod --all-containers
$ kubectl logs -laa=bb --all-containers
$ kubectl logs my-pod my-container --all-containers (err: --all-containers=true should not be specifiled with container name my-container)