Update `ember-cli-htmlbars` to 1.0.8
Update `ember-cli-htmlbars` to 1.0.8

This gets rid of a deprecation on ember 2.6.1:
```
DEPRECATION: Overriding init without calling this._super is deprecated.
Please call `this._super.init && this._super.init.apply(this,
arguments);` addon: `ember-cli-htmlbars`
    at Function.Addon.lookup
```

lynnetye/ember-trix-editor,lynnetye/ember-trix-editor