Do not call adapter.deleteRecord for a record that is already saved and deleted.
Remove DS.AttributeChange.
Add an example of sending cookie information in the header and updated confusing reopen example.
Fix error assertion's message

This fixes the error message to reflect the changes described in [Defining Relationships in Models](https://github.com/emberjs/data/blob/master/TRANSITION.md#defining-relationships-in-models).
Fix incorrect documentation for isError.

If the server returns a validation error, then isError is not set to true.
Update error messages from push and update

Error messages now include model type for ease of debugging
Add examples to the DS.Errors api docs.
Fix validation comments for

- Api docs included comments on failing client-side validation
- DS.model doesn't have client side validation
- Only code that sets errors and changes  is a result
  of an invalid response from server
[DOC beta] Clarify adapter settings with ActiveModel::Serializers
allow saving records from invalid state

tests by @alexspeller
Add a better transform example
[DOC] Fix docs for method signature of extractSingle, extractArray
[DOC] `bower install` is part of `npm install`, removing it from README
Merge pull request #1899 from bantic/update-readme

[DOC] `bower install` is part of `npm install`, removing it from README
Merge pull request #1881 from bmac/errors-examples

Add examples to the DS.Errors api docs.
Fixes a typo in the documentation of the serializeAttribute method of json_serializer.js
Merge pull request #1887 from pixelhandler/active-model-adapter-docs-settings

[DOC] Clarify adapter settings with ActiveModel::Serializers
Merge pull request #1885 from pixelhandler/validation-comments-correction

[DOC] Fix validation comments for DS.Model#isValid
Specify language as Node.js on Travis CI

Without `language` section, Travis CI detects Ruby as build language:
* https://travis-ci.org/emberjs/data/builds/24150621#L18
Use npm-scripts to run test

* https://www.npmjs.org/doc/misc/npm-scripts.html