Remove dependecy on k8s.io/kubernetes in go mod

[medyagh]

While I was trying to bump up the dependecy in go mod for k8s.io/kubernetes 1.11.3
I noticed we our go mod fails because we are importing the whole kubernetes. and I could not add a new depedency on kubectl subpackage.

Thanks to the help on golang issues, (golang/go#32864) I found out the root cause is Kubernetes is is not meant to be imported as a go module See comment golang/go#32776 (comment) . we need to import only sub-packages kuberentes and delete k8s.io/kubernetes in the the go.mod

it is a good opportunity to upgrade to 1.15.0 ( there is a few breaking api changes for apimachinary that watch.Until needs to be changed to use api machinary wait package.

if I have time I will do this, but if someone wants to take this, I would be happy to review the PR.

[josedonizetti]

I'll take this.

[medyagh]

Thank you @josedonizetti for taking this , I came across this comment kubernetes/kubernetes#79384 (comment) recomending using replace () it might be helpful to you . let me know if you have any questions

[dfang]

@medyagh currently replace() in go.mod is hard to upgrade the version of the replacement.

see golang/go#32721

[medyagh]

closed by #4719 thank you @josedonizetti