6 - Add support for file fragments using json-refs

[nicomt]

• [x] Does all of your new or changed code have unit tests?
• [x] Is overall unit test statement coverage still above 85%?
• [x] Is code style linting passing with npm run lint?
• [x] Is the related GitHub issue number included in your branch name? ex branch name: fix/12-some-bug
• [x] Is the related GitHub issue number included in your pull request title? example PR title: "12 - Fixes some bug"
• [x] Is documentation still up to date after your change?

I'm also creating a pull request soon to address #43 reusable variables. The combination of these two features should fully address #6 and #43