Support k8s versions 0.16 and above.

[Omegaice]

As described in the Deprecated APIs Removed In 1.16: Here’s What You Need To Know blog post, some of the APIs on newer versions have been removed. This manifested on my cluster by being unable to list deployments, with it giving the error Server Error: the server could not find the requested resource.

[maver1ck]

I think it's time to move this app to kube-rs
https://github.com/clux/kube-rs

[nicklan]

note that in master we're now using k8s_openapi, so I think this should be fixed