feat(etcdctl): obey the -C flag

take a comma seperated list of nodes in the -C flag and use them in the
etcd client.

etcdctl.go

@@ -8,13 +8,16 @@ import (
 )
 
 var (
-	cluster = flag.String("C", "0.0.0.0:4001", "a list of machine addresses in the cluster")
-	client  = etcd.NewClient()
+	client *etcd.Client
 )
 
 func main() {
+	cluster := ClusterValue{"http://localhost:4001"}
+	flag.Var(&cluster, "C", "a comma seperated list of machine addresses in the cluster e.g. 127.0.0.1:4001,127.0.0.1:4002")
 	flag.Parse()
 
+	client = etcd.NewClient(cluster.GetMachines())
+
 	args := flag.Args()
 
 	if len(args) == 0 {

flags.go

@@ -0,0 +1,27 @@
+package main
+
+import (
+	"strings"
+)
+
+type ClusterValue struct {
+	machines string
+}
+
+func (c *ClusterValue) String() string {
+	return c.machines
+}
+
+func (c *ClusterValue) Set(value string) error {
+	if len(value) == 0 {
+		return nil
+	}
+
+	c.machines = value
+
+	return nil
+}
+
+func (c *ClusterValue) GetMachines() []string {
+	return strings.Split(c.machines, ",")
+}