File backend should support multiple files / configuration directory(ies)

[yannh]

The File backend only supports one configuration file, or the inclusion of at most one additional file (that can be watched). It would be very convenient to be able to include all the files in a folder, or in multiple folders - a "conf.d" folder - as this makes it much easier to manage using configuration management tools such as Chef or Puppet.

Would this be a feature that others would find interesting, and what would the preferred implementation be?

[yannh]

Duplicate of #1672