master: add cluster wide lock/unlock operation in weed shell

fix https://github.com/chrislusf/seaweedfs/issues/1286

weed/server/master_server_handlers_ui.go

@@ -2,6 +2,7 @@ package weed_server
 
 import (
 	"net/http"
+	"time"
 
 	"github.com/chrislusf/raft"
 	ui "github.com/chrislusf/seaweedfs/weed/server/master_ui"
@@ -11,7 +12,7 @@ import (
 
 func (ms *MasterServer) uiStatusHandler(w http.ResponseWriter, r *http.Request) {
 	infos := make(map[string]interface{})
-	infos["Version"] = util.VERSION
+	infos["Up Time"] = time.Now().Sub(startTime).String()
 	args := struct {
 		Version    string
 		Topology   interface{}