Add kubectl-etcd plugin

[kvaps]

fixes https://github.com/aenix-io/etcd-operator/issues/212

Manage etcd pods spawned by etcd-operator

Usage:
  kubectl-etcd [command]

Available Commands:
  alarm              Manage etcd alarms
  completion         Generate the autocompletion script for the specified shell
  defrag             Defragment etcd database on the node
  forfeit-leadership Tell node to forfeit etcd cluster leadership
  help               Help about any command
  leave              Tell node to leave etcd cluster
  members            Get the list of etcd cluster members
  remove-member      Remove a node from the etcd cluster
  snapshot           Stream snapshot of the etcd node to the path.
  status             Get the status of etcd cluster member

Flags:
  -h, --help                help for kubectl-etcd
  -k, --kubeconfig string   Path to the kubeconfig file (default "/Users/kvaps/git/clients/fin-dev/infra/clusters/dev2/kubeconfig")
  -n, --namespace string    Namespace of the etcd pod (default is the current namespace from kubeconfig)
  -p, --pod string          Name of the etcd pod

Use "kubectl-etcd [command] --help" for more information about a command.