restore missing namespaces

Author: mythz

src/ServiceStack.OrmLite.SqlServer/SqlServerOrmLiteDialectProvider.cs

@@ -3,6 +3,8 @@
 using System.Data;
 using System.Data.SqlClient;
 using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
 using ServiceStack.DataAnnotations;
 using ServiceStack.OrmLite.SqlServer.Converters;
 using ServiceStack.Text;