Refactored method "onSubscribeMessage" contents to the main body for easier debugging
FB_PrimaryHost claims and initialises metrics from NBIRTH certificates
and now also updates these metrics with data found in NDATA payloads.
FB_Edge now implements FB_NodeControl which tells the Primary host which commands the Edge Node supports;
* Reboot = FALSE
* Rebirth = TRUE
* NextServer = FALSE (will be supported in a future release *)