PLT-4357 Adding stats to HA (#4638)

* PLT-4357 adding stats to HA

* PLT-4357 adding stats to HA

* Fixing getting stats from the current server

model/cluster_stats_test.go

@@ -0,0 +1,19 @@
+// Copyright (c) 2015 Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package model
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestClusterStatsJson(t *testing.T) {
+	cluster := ClusterStats{Id: NewId(), TotalWebsocketConnections: 1, TotalReadDbConnections: 1}
+	json := cluster.ToJson()
+	result := ClusterStatsFromJson(strings.NewReader(json))
+
+	if cluster.Id != result.Id {
+		t.Fatal("Ids do not match")
+	}
+}