Merge pull request #541 from cvium/fix_providermanager_guid

Change ItemId to Guid in ProviderManager

MediaBrowser.Controller/Providers/RemoteSearchQuery.cs

@@ -1,3 +1,5 @@
+using System;
+
 namespace MediaBrowser.Controller.Providers
 {
     public class RemoteSearchQuery<T>
@@ -5,7 +7,7 @@ namespace MediaBrowser.Controller.Providers
     {
         public T SearchInfo { get; set; }
 
-        public string ItemId { get; set; }
+        public Guid ItemId { get; set; }
 
         /// <summary>
         /// If set will only search within the given provider