Fix String instead of Char in HistoryService

src/NzbDrone.Core/History/HistoryService.cs

@@ -91,7 +91,7 @@ namespace NzbDrone.Core.History
 
             history.Data.Add("ElapsedTime", message.Time.ToString());
             history.Data.Add("Query", message.Query.SearchTerm ?? string.Empty);
-            history.Data.Add("Categories", string.Join(',', message.Query.Categories) ?? string.Empty);
+            history.Data.Add("Categories", string.Join(",", message.Query.Categories) ?? string.Empty);
             history.Data.Add("Successful", message.Successful.ToString());
             history.Data.Add("QueryResults", message.Results.HasValue ? message.Results.ToString() : null);