Don't close inactive session on default

This option does not have any GUI to configure it yet and causes a major behavior change that most users may not expect. Disable this behavior on default and the user want to use this feature should manually edit the config/system.xml

Signed-off-by: gnattu <gnattuoc@me.com>

MediaBrowser.Model/Configuration/ServerConfiguration.cs

@@ -163,7 +163,7 @@ public class ServerConfiguration : BaseApplicationConfiguration
     /// If set to 0 the check for inactive sessions gets disabled.
     /// </summary>
     /// <value>The close inactive session threshold in minutes. 0 to disable.</value>
-    public int InactiveSessionThreshold { get; set; } = 10;
+    public int InactiveSessionThreshold { get; set; }
 
     /// <summary>
     /// Gets or sets the delay in seconds that we will wait after a file system change to try and discover what has been added/removed