RFR 8142398: ManagementAgent.status diagnostic command only outputs the specifically set properties

[Jaroslav Bachorik]

Please, review the following change

Issue : https://bugs.openjdk.java.net/browse/JDK-8142398
Webrev: http://cr.openjdk.java.net/~jbachorik/8142398/webrev.00
This patch adds the list of the default agent properties with the info 
whether the default value has been overridden to the 
ManagementAgent.status DCMD output.

Thanks,

-JB-