public override void OnActionExecuting(HttpActionContext actionContext)
        {
            base.OnActionExecuting(actionContext);

            if (!String.IsNullOrEmpty(Roles))
            {
                var Manager = HttpContext.Current.GetOwinContext().Get<UserManager>();

                var roles = Roles.Split(',');

                if (!Manager.Authorize(roles))
                {
                    HttpResponseMessage message = new HttpResponseMessage(HttpStatusCode.Redirect);
                    message.Headers.Location = actionContext.GetRedirectUri("/Error/UnauthorizedAccess");
                    actionContext.Response = message;
                }
            }
        }