Fixes various issues relating to File Repositories and Services: U4-4014 FileRepositories offer no way to create folders, U4-4013 The models that the FileService produces causes security exceptions, U4-3993 Replace system.io calls in umbraco.scriptTasks legacy task

updates to latest CDF

src/Umbraco.Core/Persistence/SqlSyntax/SqlSyntaxProviderExtensions.cs

@@ -0,0 +1,22 @@
+namespace Umbraco.Core.Persistence.SqlSyntax
+{
+    internal static class SqlSyntaxProviderExtensions
+    {
+        /// <summary>
+        /// This is used to generate a delete query that uses a sub-query to select the data, it is required because there's a very particular syntax that
+        /// needs to be used to work for all servers: MySql, SQLCE and MSSQL
+        /// </summary>
+        /// <returns></returns>
+        /// <remarks>
+        /// See: http://issues.umbraco.org/issue/U4-3876
+        /// </remarks>
+        public static string GetDeleteSubquery(this ISqlSyntaxProvider sqlProvider, string tableName, string columnName, Sql subQuery)
+        {
+            return string.Format(@"DELETE FROM {0} WHERE {1} IN (SELECT {1} FROM ({2}) x)",
+                                 sqlProvider.GetQuotedTableName(tableName),
+                                 sqlProvider.GetQuotedColumnName(columnName),
+                                 subQuery.SQL);
+        }
+
+    }
+}