Decouple configuration from implementation with config

[ericuldall]

Add support for https://www.npmjs.com/package/config

Some pros:

• Ability to cascade configs across multiple environments as well as supporting env var overrides all in a flexible format is great.
• Users can write configs in their format of choice: json, js, yaml
• Have .gitignore local env files for developers to use keys and other configs locally that aren't committed to source control
• Ability to have nested configs accessible in any file, no more storing everything as an env var
• Type support, env vars can only be strings

We could have some common sense defaults that reduce the need for users to spend too much time in the payload config file unless performing more advanced modifications.

default.json

{
  "payload": {
    "port": 3000,
    "db": {
      "url": "",
    },
    cors: "*",
    ...
  }
}

Any thoughts on this?