public GoogleAnalyticsRequestFactory(TrackingId trackingId, bool useSslConnection = false, IWebProxy proxy = null)
        {
            if (trackingId == null || trackingId.Value == null)
            {
                throw new ArgumentException("TrackingId can't be null or empty.", "trackingId");
            }

            _trackingId = trackingId;
            _proxy = proxy;
            _useSsl = useSslConnection;
        }
        public GoogleAnalyticsRequestFactory(string trackingId, bool useSslConnection = false, IWebProxy proxy = null)
        {
            if (string.IsNullOrEmpty(trackingId))
            {
                throw new ArgumentException("TrackingId can't be null or empty.", "trackingId");
            }

            _trackingId = new TrackingId(trackingId);
            _proxy = proxy;
            _useSsl = useSslConnection;
        }