Move createSerializedForm to DS.Serializer.  Serializer calls the routine currently, but it's only defined in the JSON and Fixture implementations.
Added 'isLoading' flag to DS.State
Switch serialized/deserialized argument names
Updated against master
Merge pull request #873 from JasonKriss/patch-1

Switch serialized/deserialized argument names
Merge pull request #815 from everwakeful/master

Extend existing "meta" solution for JSON REST responses
Fix belongsTo relationships to models with id 0
Merge pull request #876 from tricknotes/fix-belongs-to-relationships

Fix belongsTo relationships to models with id 0
Remove unused local variable
Merge pull request #877 from tricknotes/remove-unused

Remove unused local variable
Merge pull request #812 from zachriggle/master

Move createSerializedForm to DS.Serializer
Allow options.defaultValue of DS.attr to be a function

This change allows the defaultValue defined for a DS.attr to be a
function, so it is possible to do something like this:

```
User = DS.Model.extend({
  createdAt: DS.attr("date", {
    defaultValue: function() {
      return (new Date());
    }
  })
});
```

This closes #878
Remove duplicate #createSerializedForm method from DS.Serializer
Merge pull request #880 from pangratz/remove_duplicate_createSerializedForm

Remove duplicate #createSerializedForm method from DS.Serializer
Typo in Bulk DELETE test

This test labeled as issuing a `PUT` instead of a `DELETE`

The actual test code does make a `DELETE` request
Merge pull request #882 from southpolesteve/patch-1

Typo in Bulk DELETE test
Merge pull request #879 from pangratz/allow_function_as_default_value

Allow options.defaultValue of DS.attr to be a function
Merge pull request #747 from fpauser/isloading-flag

Add 'isLoading' flag to DS.State
A record is found after loading its id through a hasMany relationship.

As we have now a reference for records in a hasMany relationship,
we need to make sure we load them when accessed. If the record is
`UNLOADED`, we materialize the record.

[Fixes #869]
Merge pull request #883 from Cyril-sf/has-many-bug

A record is found after loading its id through a hasMany relationship.