HTTP client refactor (#7884)

* http client refactor

* simplification

app/notification.go

@@ -695,7 +695,7 @@ func (a *App) sendToPushProxy(msg model.PushNotification, session *model.Session
 
 	request, _ := http.NewRequest("POST", *a.Config().EmailSettings.PushNotificationServer+model.API_URL_SUFFIX_V1+"/send_push", strings.NewReader(msg.ToJson()))
 
-	if resp, err := utils.HttpClient(true).Do(request); err != nil {
+	if resp, err := a.HTTPClient(true).Do(request); err != nil {
 		l4g.Error("Device push reported as error for UserId=%v SessionId=%v message=%v", session.UserId, session.Id, err.Error())
 	} else {
 		pushResponse := model.PushResponseFromJson(resp.Body)