move book support into the core

MediaBrowser.Controller/Entities/AudioBook.cs

@@ -0,0 +1,64 @@
+using System;
+using MediaBrowser.Model.Configuration;
+using MediaBrowser.Model.Serialization;
+using MediaBrowser.Model.Entities;
+
+namespace MediaBrowser.Controller.Entities
+{
+    public class AudioBook : Audio.Audio, IHasSeries
+    {
+        [IgnoreDataMember]
+        public override bool SupportsPositionTicksResume
+        {
+            get
+            {
+                return true;
+            }
+        }
+
+        [IgnoreDataMember]
+        public string SeriesPresentationUniqueKey { get; set; }
+        [IgnoreDataMember]
+        public string SeriesName { get; set; }
+        [IgnoreDataMember]
+        public Guid? SeriesId { get; set; }
+        [IgnoreDataMember]
+        public string SeriesSortName { get; set; }
+
+        public string FindSeriesSortName()
+        {
+            return SeriesSortName;
+        }
+        public string FindSeriesName()
+        {
+            return SeriesName;
+        }
+        public string FindSeriesPresentationUniqueKey()
+        {
+            return SeriesPresentationUniqueKey;
+        }
+
+        [IgnoreDataMember]
+        public override bool EnableRefreshOnDateModifiedChange
+        {
+            get { return true; }
+        }
+
+        public Guid? FindSeriesId()
+        {
+            return SeriesId;
+        }
+
+        public override bool CanDownload()
+        {
+            var locationType = LocationType;
+            return locationType != LocationType.Remote &&
+                   locationType != LocationType.Virtual;
+        }
+
+        public override UnratedItem GetBlockUnratedType()
+        {
+            return UnratedItem.Book;
+        }
+    }
+}