Add tests for calling jQuery.ajax from DS.RESTAdapter
Fix: unload record with relationships

- calling `clearRelationships` before changing record state,
  otherwise it fails, because properties try to update removed
  relationships

- Transaction commit failed when an unloaded record was in the
  `transaction.bucketForType.updated` array. Using recordIsMoving fixed
  this issue
fix test description
Add Ember.Date.parse to fix cross browser bugs parsing ISO-8601 dates
Fix typo in addRelationships documentation
Add assertion in `relatedTypes` to catch undefined relations
pushData and load now call loadData instead of duplicating code
Add assertion on BasicAdapter.findHasMany
automatically publish passing master branch builds to s3

This commit will publish passing builds of the master branch to s3 for
convenient downloading.

Files created if the build is successful:
ember-data-latest.js
ember-data-latest.min.js
ember-data-<revision>.js
ember-data-<revision>.min.js

Any *-latest*.js files will be overwritten to the build that passes and
runs `rake publish_build`.

To add credentials to your travis instance:

gem install travis
travis encrypt S3_ACCESS_KEY_ID=yourkey --add
travis encrypt S3_SECRET_ACCESS_KEY=yourkey --add

You'll also need to update the S3_BUCKET_NAME=yourbucketname in
.travis.yml
Added support for polymorphic associations.

App.User = DS.Model.extend({
 messages: DS.hasMany(App.Message, {polymorphic: true})
});

App.Message = DS.Model.extend({
  created_at: DS.attr('date'),
  user: DS.belongsTo(App.User)
});

App.Post = App.Message.extend({
  title: DS.attr('string')
});

App.Comment = App.Message.extend({
  body: DS.attr('string'),
  message: DS.belongsTo(App.Message, {polymorphic: true})
});

You need to configure the serializer to map to the correct type:

DS.RESTAdapter.configure('App.Post' {
  alias: 'post'
});
DS.RESTAdapter.configure('App.Comment' {
  alias: 'comment'
});

Initializing an alias will automatically allow you to sideload this
type. The support for sideloadAs is only for backward compatibility.

Two hooks exist for the serialization and materialization of an embedded
polymorphic association:
* `addType` that adds the record's type to the serialized data
* `extractEmbeddedType` that retrieves the record's type from the
payload.

Both hooks rely in the JSONSerializer on `keyForEmbeddedType`, which returns the string used to
represent the record's type in the payload. The default value is
`'type'`
Merge pull request #750 from Cyril-sf/polymorphic_associations

Added support for polymorphic associations.
Merge pull request #723 from klaaspieter/date-fix

Add date shim to fix cross browser issues with parsing ISO-8601 dates
Fix typo in serializer.js
Merge pull request #853 from mjallday/master

Fix a typo
use correct adapter methods
extract validation errors with correct attribute names
Merge pull request #855 from tchak/adapter-methods

use correct adapter methods
Merge pull request #849 from MikeAski/improve-assertions

Add assertion on BasicAdapter.findHasMany
Merge pull request #831 from tchak/validation-errors-fix

Extract validation errors with correct attribute names
Merge pull request #824 from arbales/master

Add assertion in `relatedTypes` to catch undefined relations