Only setting content-type to JSON if there actually is content.
Merge branch 'master' of github.com:enyo/data
Added a test for the content-type.
fixed issue #582
added adapter integration test for dirtyRecordsForAttributeChange
Failing test: 'When a record is loaded a second time, isLoaded should stay true'
Add docs directory with package.json and yuidoc.json

`EMBER_PATH=../ember-data rake preview` in ember-website does not quite
work yet. I don't have time at the moment to get it working completely,
but let's have the docs directory as a starting point.
Add live query test for RecordArray
Potential fix for #731
Use Ember.isNone for null check instead of !

Using !id to check for a null belongsTo id was causing relationships to be treated as missing.
Remove unused method

DS.Model#setProperty is no longer working.
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
Enforce more methods on serializer

* extractId
* extractAttribute
* extractHasMany
* extractBelongsTo
* createSerializedForm
* addId
* addAttribute
* addHasMany
* addBelongsTo
A blank value should be converted to null rather than zero
When saving records with null belongsTo relationships, the relationship is serialized with a null value
Update fixtures to support the new polymorphic association feature
Merge pull request #864 from endash/fix/fixtures-polymorphic

Update fixtures to support the new polymorphic association feature
Merge pull request #752 from darthdeus/live-query-test-for-record-array

Add live query test for RecordArray
Merge pull request #785 from tricknotes/remove-unused-method

Remove unused method