Removed Trakt to Tvdb migration workaround, so it actually removes the tvrageid when skyhook says so.

src/NzbDrone.Core/Tv/SeriesService.cs

@@ -183,11 +183,6 @@ namespace NzbDrone.Core.Tv
                 }
             }
 
-            if (series.TvRageId == 0)
-            {
-                series.TvRageId = storedSeries.TvRageId;
-            }
-
             var updatedSeries = _seriesRepository.Update(series);
             _eventAggregator.PublishEvent(new SeriesEditedEvent(updatedSeries, storedSeries));