Check against `null` and `undefined`
remove revision reference.

https://github.com/emberjs/data/commit/7c01dd5fef7667c17da1b78483235306c9356421
Add failing integration test to expose bug #1005
Fix: record must be invalid on 422
RESTAdapter: reject with xhr only
Replace references to jQuery with Ember.$
Merge pull request #1008 from madadam/rest-adapter-422-fix

Fix for #1005: RESTAdapter incorrectly marking records as error on 422, instead of invalid
Assert post is dirty
Merge pull request #1010 from ahawkins/assert-root-is-dirty

Assert root is dirty in embedded tests
bump ember-source to 1.0.0-rc.5
Support `Ember::Data::VERSION`

``` ruby
require 'ember/data/source'

Ember::Data::VERSION #=> "0.13"
```
Merge pull request #1019 from tricknotes/version

Support `Ember::Data::VERSION`
Remove unused tasks

Currently ember is managed by `ember-source` gem.
Remove unnecessary comment
Remove unused helper
Remove unused variables
Merge pull request #1021 from tricknotes/remove-unused-tasks

Remove unused tasks
Merge pull request #1020 from tricknotes/remove-unused-valiables

Remove unused valiables
English, do you speak it?
Merge pull request #1028 from bcardarella/grammar

English, do you speak it?