add support for multiple config files and nested config files

[dcblogdev]

This PR ads support for multiple root level config files but also nested folders.

for example

config/
    admin/admin.php
    admin.php
    config.php
    user.php

Then to use them config('module.file.name') for example config('books.service.name') to load config/service.php from a module called Books

Usage of the default config.php is unchanged. ie config('module.name') will load the name key from module/config/config.php