Update "Underscored Keys, `_id` and `_ids`" section

ActiveModelSerializer is finished and works like magic.

Furthermore, the previous code was not enough to make ember data work with underscored attributes (see issue #1428)
Correctly define window/global DS namespace in IE7/8.

In IE7/8, defining DS globally without directly defining it on
window.DS causes it to not appear in the for..in loop that
processes namespaces inside of findNamespaces()

https://github.com/emberjs/ember.js/blob/master/packages/ember-runtime/lib/system/namespace.js#L117

This causes Ember.Namespace.NAMESPACES_BY_ID to contain an undefined
key instead of DS, which leads to issues when resolving across different
namespaces (such as the DS namespace when using DjangoRESTAdapter), or
when generating toString() outputs of the DS namespace or child objects.

This change allows one existing, failing test to pass in IE8:

https://github.com/emberjs/data/blob/c04b8e47c7de8b158d16bd4850744fec796ca05f/packages/ember-data/tests/unit/model_test.js#L57

which fails because the DS part of the expected toString() output
is missing.
Merge pull request #1439 from craigteegarden/ie7-8-missing-DS-global-namespace

Correctly define window/global DS namespace in IE7/8.
Merge pull request #1437 from cibernox/patch-1

Update "Underscored Keys, `_id` and `_ids`" section
Remove unused `didReload` hook.
[doc] add inline doc for optional query in store.filter
Merge pull request #1444 from sly7-7/patch-2

[doc] add inline doc for optional query in store.filter
Bump version
Remove old-tests.
Update `ember-dev` to (b0b12c4).

Updates `ember-dev` to (b0b12c4) which includes the following changes:

* Will not attempt to `unshallow` a full git repo
* Makes default test suite (packages only) run with features enabled and
  disabled.
* Fixes bug where the wrong Project name is used in the auto-generated
  CHANGELOG.
* Allows overriding the build type. (Simply set `ENV['BUILD_TYPE']='canary'`)
* Add `ember:generate_static_test_site` task to create a static HTML
  file for running the test suite.
* Add custom test results gathering for use in cross-browser testing.
* Make sure that the test file being used in the `Assetfile` is prefixed
  with the proper dasherized project name (prior to this Ember Data
  tests were still named `ember-tests.js` and now they will be
  `ember-data-tests.js`).
* Fixes issue where local `rake test` runs would attempt to perform git
  operations (`checkout` and `cherry-pick`). Now git operations will
  only be attempted if `ENV['CI']=true`.

For further reference:

https://github.com/emberjs/ember-dev/compare/0c0743979a...b0b12c4758e26
Merge pull request #1452 from rjackson/update_ember-dev

Update `ember-dev` to (b0b12c4).
Generate static site tests.

This will publish a ember-tests.html static test site along with the
builds. This makes it extremely simple to test the latest
canary/beta/release builds on various devices. It is also critical to
the cross-browser testing that we have been working on.
Merge pull request #1453 from rjackson/static_test_generator

Generate static site tests.
Ensure that async hasMany is always a promise
Update rest_adapter.js

Cleared up some ambiguity in the comments around createRecord and deleteRecord
Use consistent versioning.
Merge pull request #1456 from rjackson/use_consistent_versioning

Use consistent versioning.
Merge pull request #1455 from eccegordo/patch-3

Update rest_adapter.js
Minor documentation fix
Documentation Update rest_adapter.js

Went through the file and did a little more word smithing, making more consistent the description of HTTP methods used.