updated config to follow established pattern

[JustDaile]

I think this pattern for the config is good and has some advantages. So I've updated the authentication service as follows:

• The service package defines the authentication service configuration
• The environment config loader initializes a instance of the configuration based of the environment variables provided at runtime.
• The main initializes the environment config and injects the config where needed.

Can we maintain this pattern for now? We can discuss alternatives in chat if you'd prefer.