Moved a few classes into their own files

MediaBrowser.Model/Entities/SubtitleStream.cs

@@ -0,0 +1,17 @@
+using ProtoBuf;
+
+namespace MediaBrowser.Model.Entities
+{
+    [ProtoContract]
+    public class SubtitleStream
+    {
+        [ProtoMember(1)]
+        public string Language { get; set; }
+
+        [ProtoMember(2)]
+        public bool IsDefault { get; set; }
+
+        [ProtoMember(3)]
+        public bool IsForced { get; set; }
+    }
+}