Merge pull request #361 from cvium/fix_userid_type

DeviceQuery: change UserId to GUID

Emby.Server.Implementations/Devices/DeviceManager.cs

@@ -145,7 +145,8 @@ namespace Emby.Server.Implementations.Devices
                 HasUser = true
 
             }).Items;
-
+            
+            // TODO: DeviceQuery doesn't seem to be used from client. Not even Swagger.
             if (query.SupportsSync.HasValue)
             {
                 var val = query.SupportsSync.Value;