Support a `--token` flag

[Yuval Avrahami]

Adding a --token flag would improve usability, at least for me. The command would then look something like:

$ kubeletctl --token=<token> --server=<addr> <command>

Using a token is probably also possible if you create an kubeconfig file and then use the --config flag, but I'd rather not do that.

[Eviatar Gerzi]

I added support in --token and --token-file flags, I tested and it worked fine from my end.

I published new version 1.8:
https://github.com/cyberark/kubeletctl/releases/tag/v1.8

Thanks for the suggestion :)

[Yuval Avrahami]

Works on my side as well, thank you