Fix active_model_serializer link

Repo was moved to rails-api organization
Fix typo in store error message
Extract embedded `belongsTo` records properly

`sideload` won't consider relationships/embedded records, by using
`extractRecordRepresentation` we'll recurse into the record (similarly
to `extractEmbeddedHasMany`).
Use of references instead of clientId
Added failing test for embedded belongsTo JSON serialisation
fix includeId typo for embedded belongsTo records in JSON serialisation
Remove unused model state
generateIdForForRecord should reify adapter
set default_external for ruby 1.9
Address issue with embedded hasMany creation

Fixes #633. This ensures that when creating a new
record in an embedded hasMany relationship, either
via `post.get('comments').createRecord` or via
`Comment.createRecord({ post: post })`, both the
child and parent will become dirty.

This retains the "dirty tree" semantics, which
will walk up and down the tree of embedded
relationships and mark things dirty.
Created embedded records should dirty parent

Previously, embedded records (those without IDs)
that were created via ManyArray's `createRecord`
method were not properly being saved, nor dirtying
the parent's tree.

This commit ensures that an embedded record's
parent is saved on its reference when it is
added to the many array for the first time.
Prevent duplicate handling of sideloaded values when there are complex relationships
Support use without prototype extensions
Fixed tests for Ember master
Switch to ember-dev for tooling
Update ember-dev to fix tests
Extract data construction from create/update/deleteRecord and create/update/deleteRecords to allow more flexibility to developpers extending default RESTAdapter.
Use an *extractFoo* convention for new data extraction hooks in ember-data RESTAdapter.