Update code to use `{{this.property}}` syntax where appropriate

[locks]

In an effort to clarify where a value in a template interpolation comes from ({{}}), we started prefixing local properties (that belong to the Controller/Component of the respective template) with this, like the following:

import Component from '@ember/component';

export default Component.extend({
  framework: 'Ember.js'
});

{{this.framework}}

This repository needs to be updated to match v3.6 of the Guides.

[Windvis]

I can take a look at this tonight.

[jenweber]

closed with #113

Thank you!!! 🎉