Converting code examples for Octane has refreshed a discussion about using jQuery in trivial code examples. I think we should refactor code examples that feel dated due to using $.getJSON. See #33 for my prior hang ups. Tangential to #499.

current usage in release guides

• https://github.com/ember-learn/guides-source/blame/master/guides/release/models/index.md#L114
• https://github.com/ember-learn/guides-source/blame/master/guides/release/models/index.md#L143
• https://github.com/ember-learn/guides-source/blame/master/guides/release/models/finding-records.md#L93
• https://github.com/ember-learn/guides-source/blame/master/guides/release/routing/asynchronous-routing.md#L38

why use window.fetch?

I propose we use window.fetch for at least 3 reasons:

1. it is widely supported by modern browsers.
2. In a land of jQuery free Ember applications, why should we promote depending on the entire jQuery library for a single function?
3. Easier teaching and mental model. By aligning with a web standard, we leverage existing teaching and developer experience. For new developers it gives them a helpful tool that could be considered a best practice in web development. Fetch's Promise based design flows nicely with concepts taught throughout the Ember guides and modern asynchronous web programming.