missing this in SortableMixin#contentArrayDidChange causes observers not to be properly removed
Add needs to controllers
add test for SortableMixin bugfix
Make `model` an alias for `content` on controllers
Merge pull request #1682 from gabesmed/master

Bugfix in SortableMixin; sortProperty observers not being correctly removed
sub containers should inherit resolver
Added VagrantFile and chef cookbooks to ease ember build for developers.
Doc explaining how to build ember with Vagrant VM
Update gitsubmodules urls to public repos.
Merge pull request #1706 from tchak/sub-containers-resolver

sub containers should inherit resolver
make container a module
Complete concatenated properties doc

Documenting the feature of adding a single property should just add it into the related array
Merge pull request #1710 from sly7-7/patch-1

Complete concatenated properties doc
Merge pull request #1707 from tchak/container-as-module

make container a module
Fix trailing slash issue. Fixes #1691
Merge pull request #1708 from bobey/master

Added a VagrantFile to ease emberjs build for newcomers
Update gitignore.
Remove pointless check for native Array replace.

The real function is called splice, which is what the “shim” was calling anyway.
ArrayController learned itemControllerClass.

```javascript
App.ItemController =
  Em.ObjectController.extend();

var arrayController = Em.ArrayController.create({
  itemControllerClass: 'ItemController',
  content: Em.A([0, 1])
});

controller.objectAtContent(0);               // an instance of ItemController
controller.objectAtContent(0).get('content') // 0
```

This partially addresses #1637, but makes no attempt at supporting reusable
views.