update models to use new ModelBase

Oqtane.Shared/Models/Folder.cs

@@ -6,7 +6,7 @@ namespace Oqtane.Models
     /// <summary>
     /// Describes a Folder in Oqtane
     /// </summary>
-    public class Folder : IAuditable
+    public class Folder : ModelBase
     {
         /// <summary>
         /// ID to identify the folder
@@ -59,22 +59,6 @@ namespace Oqtane.Models
         /// </summary>
         public bool IsSystem { get; set; }
 
-        #region IAuditable Properties
-
-        /// <inheritdoc />
-        public string CreatedBy { get; set; }
-
-        /// <inheritdoc />
-        public DateTime CreatedOn { get; set; }
-
-        /// <inheritdoc />
-        public string ModifiedBy { get; set; }
-
-        /// <inheritdoc />
-        public DateTime ModifiedOn { get; set; }
-
-        #endregion
-
         #region Extended IAuditable Properties, may be moved to an Interface some day so not documented yet
 
         public string DeletedBy { get; set; }