Ember: remove response
Ember: question history
Account Management

- Adds Ember classes needed to edit account information
- Adds custom Ember Simple Auth session that gets the current user based on the session's user ID
- Adds ActiveModel::Errors serializer to ensure model mutations are possible after an error occurs
-- If errors are not properly returned to Ember, models remain 'in flight' and cannot be modified
- Monkey patches ActiveModel::Serializers to not aggressively use ArraySerializer
- Extends DoorkeeperTokensController to add the user's ID when an authorized token is returned