etcdctl: two member fixes

437a10d (Brandon Philips, 4 minutes ago)
   etcdctl: take a name and print out the initial cluster

   To help the user lets print out the configuration that they will need to
   give to their new member:

   $ etcdctl member add infra4 http://localhost:7004 added member
   9bf1b35fc7761a23 to cluster ETCD_NAME="infra4"
   ETCD_INITIAL_CLUSTER="node2=http://localhost:7002,node3=http://localhost:7003,infra4=http://localhost:7004,node1=http://localhost:7001"

   This is a little weird because the API doesn't take a name so the user
   gives us a name and we just pass it on through.

8f3be20 (Brandon Philips, 37 minutes ago)
   etcdctl: add help on the members subcommands
Is this useful? `fmt.Printf("ETCD_INITIAL_CLUSTER_STATE=existing")`