Add config module

[mattremmel]

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[mattremmel]

@dcadenas heres the way I usually set up a config module for my projects. I inlined an example of using the config, but usually I would have that in the same module as the object/actor that needs the config. Its a pretty minimal example, but I would also be happy to show you some more 'real' examples of how I've used it in one of our production monitors.

[mattremmel]

The main benefit, is that all the configuration can be loaded and parsed at startup, so that you can fail fast, and code that depends on that config are able to be made infallible, since the fallible fetching and parsing the config was already done before its construction. It also helps to make all the config typesafe once you go to use it.

[mattremmel]

I forgot to mention. This allows easily overlaying a default config, with an environment based file config thats dynamically loaded based on environment variable, then a local config which is added to .gitignore, so that you can put keys/etc into there, and then any config item can be overwritten with an environment variable, which has the highest precedence.

[dcadenas]

Looks great!