Added configuration validation for content imaging settings.

src/Umbraco.Core/Configuration/Models/ImagingAutoFillUploadField.cs

@@ -0,0 +1,23 @@
+using System.ComponentModel.DataAnnotations;
+using Umbraco.Core.Configuration.Models.Validation;
+
+namespace Umbraco.Core.Configuration.Models
+{
+    public class ImagingAutoFillUploadField : ValidatableEntryBase
+    {
+        [Required]
+        public string Alias { get; set; }
+
+        [Required]
+        public string WidthFieldAlias { get; set; }
+
+        [Required]
+        public string HeightFieldAlias { get; set; }
+
+        [Required]
+        public string LengthFieldAlias { get; set; }
+
+        [Required]
+        public string ExtensionFieldAlias { get; set; }
+    }
+}