When using get with path (eg. get('foo.bar.baz')), get method is called
only on the current object and computed property will be called. Because
there is no easy way to overwrite the computed property, I moved
incomplete record loading to ember-data. It's not DRY and it should be
rewritten, but I don't want to do it at this point as we will need to
completely rewrite it when upgrading ember-data.
