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.
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
Merge pull request #863 from robmonie/null_belongs_to_serialization

When saving records with null belongsTo relationships, the relationship ...
Merge pull request #862 from bradleypriest/blank-number

A blank value should be converted to null rather than zero
Merge pull request #712 from jetako/property-change-typo-fix

Fixed attribute change notification when a record is created with initial values.
Merge pull request #717 from tchak/serializer-interface

Enforce more methods on serializer
Add more assertions to BasicAdapter primitives