How should basePaths for multiple environments be specified?

For instance, development vs test vs staging vs production?

We've been putting them in a parallel `basePaths` like:

```
{
  basePath: 'http://api.example.com'
  basePaths: {
    development: 'http://api.dev-example.com',
    test: 'http://api.test-example.com',
    stage: 'http://api.stage-example.com',
    production: 'http://api.example.com'
  }
}
```
