Initial vision of nested configuration
:bug: Forgot to change from "in" to "of"
:bug: Fix opening a file without overridden scope
Clean up the returned object using a whitelist
Add a few end-to-end tests to ensure everything works

Some of this code is pretty ugly and will need to be refactored,
but the tests all work :grinning:
Merge pull request #2 from thomasjo/ld-nested-config

Initial vision of nested configuration