Fix error assertion's message

This fixes the error message to reflect the changes described in [Defining Relationships in Models](https://github.com/emberjs/data/blob/master/TRANSITION.md#defining-relationships-in-models).
allow saving records from invalid state

tests by @alexspeller
Use `package.json` as gem version
Fix to update ember-data version

Now, ember-data is versioned as 1.0.0-beta.8+canary.
[BUGFIX] Add missing support for belongsTo in DS.EmbeddedRecordsMixin

- active_model_serializer gem `has_one` setting allows embedding objects
- Add attrs options for serialize/deserialize using records or ids
- Add attrs options for not serializing relationships using serialize:no
-Add a hook called removeEmbeddedForeignKey for optional removal of foreign key reference from the embedded record
Merge pull request #1637 from pixelhandler/ams-has-one-embedded-belongs-to

[BUGFIX] DS.EmbeddedRecordsMixin support for belongsTo relationships
[Bugfix] when a record which exists in an adapterPopulatedRecordArray is destroyed, it is also now removed from the array

@goDownhillFast & @joebartels
Merge pull request #1923 from Vestorly/adapter_populated_record_arrays_delete

[Bugfix] when a record which exists in an adapterPopulatedRecordArray is...
Setting a filter function on a filteredRecordArray should only cause 1 re-filter per run-loop
Merge pull request #1924 from stefanpenner/prevent-filter-function-churn

Setting a filter function on a filteredRecordArray should only cause 1 r...
filteredRecordArray derived from filterFn + query, should retain its query (just as adapterPopulated does)
Merge pull request #1926 from stefanpenner/filtered-record-array-from-query-should-retain-query

filteredRecordArray derived from filterFn + query, should retain its que...
Fix publishing of builds.
Merge pull request #1836 from lulezi/patch-1

Fix error assertion's message
[DOC] Fix jsdoc for `Serializer#extractSingle`

Now the argument `requestType` is unused.
This commit is the part of be797b992 .
Merge pull request #1930 from tricknotes/jsdoc

[DOC] Fix jsdoc for `Serializer#extractSingle`
Put the initialization docs back with the initializers
Update the docs on pushPayload to clarify how model is used
Merge pull request #1932 from mixonic/push-payload

Push payload
Merge pull request #1889 from tchak/invalid-save

Allow saving records from invalid state