Z-Wave: Node Deletion & Add Controller IsFailedNode

A Z-Wave node can only be deleted if its present in the controllers
"Failed List" resident in its own NVRAM.
Added the Z-Wave IsFailedNode Message Class.
Added new Failed status if the controller has it flagged as failed in
its own database.
This then allows a node to be deleted.
Visibility of the "Delete Node" button uses this new logic.
Z-Wave: Node Deletion - improve FailedNode logic

Remove unnecessary call to delete node xml - already done on success
event at controller level.
Allow a FAILED node to be set to alive again if packets are received
from it.
Heal process of failed nodes handled correctly.
Z-Wave: Failed Node - Add "Failed" boolean status

Added "Failed" status to config
Consolidated status info.
Removed the 'failed' status and changed the 'node stage' to provide the enum so the client side can see what state the device is in.
Move requestIsFailedNode to NetworkMonitor

To ensure always gets called when a node is marked as dead during
runtime.
Thanks to Chris for the advice!
Merge pull request #1516 from wezhunter/zwave-delete-node-improvements

Z-Wave: Node Deletion & Add Controller IsFailedNode