[Noah-Huppert]

I made this tool to solve the problem of being slowed down by having to add the `--namespace` argument to every single `kubectl` command invocation:

  # Before
  kubectl --namespace foo-bar get pods  
  kubectl --namespace foo-bar describe pod/bazz  
  kubectl --namespace foo-bar exec bazz
  
  # After  
  kubens use foo-bar

  kubectl get pods  
  kubectl describe pod/bazz  
  kubectl exec bazz  

I hope this helps others who have encountered the same issue.