Proposal to add 1-arg behavior to config.setModuleDefaults(moduleName, defaults). If the 2nd argument isn't specified, it loads defaults from the /config directory within the module specified by moduleName.

This serves many purposes:

* It moves submodule configurations out of code
* It puts submodule configuration into a well known place
* It provides a common place to put configuration documentation
* It allows running the submodule as an app, with overrides for tests, etc.
* It prevents namespace clash by utilizing the submodule package name
* It doesn't break backwards compatibility
* The 2-arg mechanism can be deprecated, with ample warning

When this change is made, change the wiki page to document only this behavior. Make a note about the features the 2-arg behavior doesn't have, and that it will be going away in the future (at least 1 year).

Establish a convention for submodules that they be configured by passing overrides to the module constructor, or by overrides in the app /config directory. This allows the submodule to be used by apps that also use node-config as well as apps that use other configuration systems.