Add new API

[wojtekmach]

Ref: #82

This is extracted from https://github.com/wojtekmach/goth, a fork we've created at Dashbit a while ago.

[lytedev]

Thanks for linking this fork! It's looking like this upstream is pretty inactive. Perhaps we can move this repo to the Dashbit one? I'm not sure exactly what all that entails, but I imagine it will take some cooperation from both you and @peburrows?

[wojtekmach]

@peburrows invited me to help maintaining this repo and I intend to upstream all the changes from my fork and release them as goth v1.3.0 on Hex so stay tuned!

[peburrows]

I have no major feedback that would change the core approach here — looks great. I'm so glad someone else cares enough about this little library to give it the attention I haven't had the time to over the last year or so!

[ludwikbukowski]

what about the idea; instead of passing the variable name, it could digest pure value and let allow the client to configure System.fetch_env!/1 on hiw own

[wojtekmach]

note this is an attempt at an upgrade guide. People should be moving away from code like this to what is mentioned below. :)

[ludwikbukowski]

ah, you're right! then, on the same page, thanks