env-based config

- change `api.configData` to `api.config`
- move `config.js` into a `config` directory, rename it to `config/config.js`
- allow for environment-specific overrides to `confg.js`
  - use `NODE_ENV` to choose environment
  - allow for ENV specific overrides via files (`config/development.js`, `config/production.js`, etc)
- update tests
- update generators
  - provide a slug `production.json`