Add management for configs

This PR enable the ability to manage configuration settings via adding a mongoose schema and Linz will convert this to a document and store it against linzconfigs collections.

To-do:
- [x] Linz to load config files and create documents in linzconfigs collection
- [x] Add router control for accessing the list of config in the Admin UI
- [x] Add navigation item to access the list of configs
- [x] Editing capability for configs via Admin UI
- [x] Overview display for config
- [x] Ability to reset config to default values
We need some try... catch action in here. If the directory doesn't exist, it should use debugConfigs to state that no configs were found, and that the directory didn't exist.