Starting a discussion about API development

This pull is definitely WIP -- I would like to make significant changes -- but at a minimum it adds

* GET methods
* saner defaults
* strawman to hate on while we build a more robust API

I'm curious what folks would use as a model -- Octokit from Github? 

I'd also like to propose:

* higher-level library (eg faraday, sawyer)
* versioning for the API -- sooner it starts, the better -- but requires corresponding change to main discourse branch
* talk around authentication options

I guess this should move to meta, so pasting it there too