This moves the whitelist for nodes' "normal" attributes to a config
file, which is loaded live during every run and applied in memory in
case the node's local file hasn't been updated before the client run.
Fixes allowed attributes being overwritten/removed in the node info
JSON files.
This has been the only way I managed to make `chef generate cookbook
COOKBOOK_NAME` set the default values
This is not documented, there is an issue open about it:
https://github.com/chef/chef-cli/issues/54