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.
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.
Merge pull request #766 from brigham/master

Make belongsTo recognize id 0
Rename none to isNone
Merge pull request #743 from CrowdStrike/yuidoc

Add docs directory with package.json and yuidoc.json
Merge pull request #731 from go1dfish/reload-isloaded

Failing test: 'When a record is loaded a second time, isLoaded should stay true