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
Improve error message

`fixture` is an instance of `Object`.

Before:
```
the id property must be defined for fixture [Object object]
```

After:
```
the id property must be defined for fixture {"foo": "bar"}
```
Use `toString` if environment doesn't support `JSON.stringify`
Remove unused var declaration
upgrade ember
utilize the new Computed#readOnly
Merge pull request #810 from bradleypriest/patch-4

Remove unused var declaration
Merge pull request #809 from JasonKriss/terminology-cleanup

Update to 'relationship' terminology
Merge pull request #805 from tricknotes/improve-error-message

Improve error message
Remove unused variables and helper functions
Merge pull request #817 from tricknotes/remove-unused

Remove unused variables and helper functions
prefer public DI api on the application instance when possible.
bump ember test-version
Merge pull request #819 from stefanpenner/upgradeEmberAndReadOnly

Upgrade ember so Computed#readOnly is available
Add assertion in `relatedTypes` to catch undefined relations
Support create/update/delete