1. volume server auto detect clustered master nodes

2. remove operation package dependency on storage

go/operation/list_masters.go

@@ -0,0 +1,27 @@
+package operation
+
+import (
+	"code.google.com/p/weed-fs/go/glog"
+	"code.google.com/p/weed-fs/go/util"
+	"encoding/json"
+)
+
+type ClusterStatusResult struct {
+	IsLeader bool
+	Leader   string
+	Peers    []string
+}
+
+func ListMasters(server string) ([]string, error) {
+	jsonBlob, err := util.Get("http://" + server + "/cluster/status")
+	glog.V(2).Info("list masters result :", string(jsonBlob))
+	if err != nil {
+		return nil, err
+	}
+	var ret ClusterStatusResult
+	err = json.Unmarshal(jsonBlob, &ret)
+	if err != nil {
+		return nil, err
+	}
+	return ret.Peers, nil
+}