static void ApplePusher_OnInvalidToken(IPusher sender, InvalidTokenEventArgs eventArgs)
        {
            var device = _context.Devices.FirstOrDefault(d => d.Token.Equals(eventArgs.Token));

            if (device != null)
            {
                _logger.Info("Removing invalid/expired token: {0}", eventArgs.Token);
                _context.Devices.Remove(device);
                _context.SaveChanges();
            }
        }