Need a mechanism to detect and remove failed ZWave nodes

[dhylands]

The ZWave controller will eventually mark a node as failed if it stops responding after a while. We need a way to tag these nodes as failed, and a way to call the Manager::RemoveFailedNode C++ API.

I think that this can be reproduced by adding a node and then factory resetting it. You can then add the node a second time, and the first nodeId will stick around and should eventually get marked as failed.

[benfrancis]

@dhylands In my testing, un-pairing a Z-Wave device does not remove it from the list of devices the adapter reports. Shouldn't a device be removed immediately when manually un-paired? This is a bit annoying because at the moment you can get lots of duplicate devices in the add device dialog.

[dhylands]

It's possible it's not getting removed from everywhere. I'll take a look.

[mrstegeman]

These are no longer reported to the UI, at least. Fixed by #488

[mrstegeman]

Moved: WebThingsIO/zwave-adapter#31