removed private unused properties in ManyArray
Merge pull request #2275 from sly7-7/remove-unused-field

removed private unused properties in ManyArray
Add a test for an async belongsTo with buildURL
preload the belongsTo to be available synchronously
Update jsfiddle/jsbin to latest ember-data in CONTRIBUTING.md
[DOCS] Cleanup "USING EMBEDDED RECORDS" API readability
Remove extra space in code example
Merge pull request #2283 from knownasilya/patch-1

[DOCS] Cleanup "USING EMBEDDED RECORDS" API readability
Serialize belongsTo where id===null as null
Improve comments for the inverseFor method
Added implicit relationships

We now correctly remove a record from a manyArray when it is deleted
even if the record does not have a belongsTo relationship to the manyArray