Added critic rating as a sort order

MediaBrowser.Model/Querying/ItemFields.cs

@@ -21,6 +21,11 @@ namespace MediaBrowser.Model.Querying
         /// </summary>
         Chapters,
 
+        /// <summary>
+        /// The critic rating summary
+        /// </summary>
+        CriticRatingSummary,
+
         /// <summary>
         /// The date created of the item
         /// </summary>

MediaBrowser.Model/Querying/ItemSortBy.cs

@@ -62,5 +62,10 @@ namespace MediaBrowser.Model.Querying
         /// The play count
         /// </summary>
         public const string PlayCount = "PlayCount";
+        /// <summary>
+        /// The critic rating
+        /// </summary>
+        public const string CriticRating = "CriticRating";
+
     }
 }