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
Hey @sandytrinh,

Now that we've made this asynchronous, when you start the application, the application started message ('MMS app started and running on port 3900') actually appears before the app has finished initialised.

It would be good to have this appear at the end, as it previously did.

cheers,
Scott.