Add Ruby version to Gemfile and for rbenv.

We are going to enforce Ruby 2.0.0 in use here.
Add gem dependency: json

We are going to be using JSON as the configuration file format and
transmission format (at least, for now) between the API servers. It
would be best to use a native extension.
Add simple binstub with standalone support.

This is a simple CLI that we'll use to startup the tool. It is able to
use a precomputed Bundler load path for faster startup times.