Allow Nodeserver to specify files to be included in a backup/restore

[jimboca]

We need a way for the nodeserver to specify files to include in the backup
Harmony and lifx need it, and maybe others https://forum.universal-devices.com/index.php?/topic/27833-How-to-painlessly-migrate-RPi-to-Polisy#entry273042
This needs to be a pattern or glob, like *.yaml or allow nodeserver to add to the list on the fly.