Support kubectl standard flags

[neowulf]

This is an awesome project! Thank you for working on this much needed feature!

I installed this plugin via:

kubectl krew install df-pv

I am unable to use the standard kubectl flags to switch the context and the namespace and I get this error:

$ kubectl --context $kubecontext df-pv                                                                                                        
Error: flags cannot be placed before plugin name: --context

I work with multiple clusters at a time and so setting the kubectx would be time consuming.

[RaulButuc]

Should also support multiple output formats -o