When multiple instances of node-config are loaded, only one instance will get module defaults inserted on setModuleDefaults(). Other configurations will be duplicated, so it's only an issue for submodule defaults.

This is related to issue #225 because defaults loaded under submodule /config directories will have the same problem as defaults loaded using setModuleDefaults().

Some ways this could be addressed:

* Assuring copies are identical (hard)
* Having all copies work on a single global config (messy)
* Assuring only one instance is loaded (not sure this is possible)
* Others?

If we were to resolve this issue, which one makes most sense?