message: Use relationship link for creating new draft regs
diff: import DS from 'ember-data';
  -import config from 'ember-get-config';
  -
  -import pathJoin from 'ember-osf-web/utils/path-join';
  import OsfAdapter from './osf-adapter';
  -const { OSF: { apiUrl, apiNamespace } } = config;
  -
  export default class DraftRegistration extends OsfAdapter {
  urlForCreateRecord(_: string, snapshot: DS.Snapshot) {
  - return pathJoin(
  - apiUrl,
  - apiNamespace,
  - 'nodes',
  - snapshot.record.belongsTo('branchedFrom').belongsToRelationship.members.list.firstObject.id,
  - 'draft_registrations',
  - );
  + return snapshot.record.belongsTo('branchedFrom').value()
  + .links.relationships.draft_registrations.links.related.href;
  }
  }
  