Update CHANGELOG.md

Updated CHANGELOG for PR [#1117](https://github.com/stefanpenner/ember-cli/pull/1117)
Updated commit to resolve conflicts
Merge pull request #1128 from quaertym/master

Update CHANGELOG.md
Allow addons to specify load ordering.

* Bring topsort algorithm from Ember (used for initializer ordering).
* Allow addons to use `ember-addon` key which resolves to an object with
  `main`, `before`, and `after` keys.
* Allow `ember-addon: { main: 'foo.js'}` as alternative to
  `ember-addon-main` in the `package.json`
* Change `availableAddons` to return an object with the `package.json`
  contents of each addon (was previously being looked up twice).