Explicit testing of min-version on settings..

[grtjn]

The ml5-config.xml, ml6-config.xml, etc, contain settings that are supported, but settings that are disallowed for older versions are not explicitly checked for VERSION_NOT_SUPPORTED exceptions. Would add to the robustness of Roxy..

[grtjn]

Given the potential move to Management REST api thinking this is not worth the effort at the moment. Closing with won't fix.