PLT-2899 adding clustering of app servers (#3682)

* PLT-2899 adding clustering of app servers

* PLT-2899 base framework

* PLT-2899 HA backend

* PLT-2899 Fixing config file

* PLT-2899 adding config syncing

* PLT-2899 set System console to readonly when clustering enabled.

* PLT-2899 Fixing publish API

* PLT-2899 fixing strings

api/general.go

@@ -69,7 +69,6 @@ func ping(c *Context, w http.ResponseWriter, r *http.Request) {
 	m := make(map[string]string)
 	m["version"] = model.CurrentVersion
 	m["server_time"] = fmt.Sprintf("%v", model.GetMillis())
-	m["node_id"] = ""
 	w.Write([]byte(model.MapToJson(m)))
 }