default IP to "localhost"

so that the master can know the ip address.

weed/command/volume.go

@@ -43,7 +43,7 @@ func init() {
 	cmdVolume.Run = runVolume // break init cycle
 	v.port = cmdVolume.Flag.Int("port", 8080, "http listen port")
 	v.publicPort = cmdVolume.Flag.Int("port.public", 0, "port opened to public")
-	v.ip = cmdVolume.Flag.String("ip", "", "ip or server name")
+	v.ip = cmdVolume.Flag.String("ip", "localhost", "ip or server name")
 	v.publicUrl = cmdVolume.Flag.String("publicUrl", "", "Publicly accessible address")
 	v.bindIp = cmdVolume.Flag.String("ip.bind", "0.0.0.0", "ip address to bind to")
 	v.master = cmdVolume.Flag.String("mserver", "localhost:9333", "master server location")