Fixed to category handling

Application/Entities.cs

@@ -1,6 +1,7 @@
 using System.Collections.ObjectModel;
 using System.ComponentModel;
 using System.Data.Entity.Infrastructure;
+using System.Linq;
 
 namespace FeedCenter
 {
@@ -48,6 +49,11 @@ namespace FeedCenter
             }
         }
 
+        public Category DefaultCategory
+        {
+            get { return _allCategories.First(c => c.IsDefault); }
+        }
+
         #endregion
 
         #region All feeds