When actions were first implemented, the action's ID was provided to

the model as an actionId attribute. This wasn't marked as the model's

attribute, so it didn't properly function as an ID for lookup purposes.
To keep things clean and standard, this has been renamed to id. This

may have some theoretical fallout if anyone has actions with custom

views that reference this.get('actionId'), but it's unlikely any

third-parties will truly be affected. If needed, we could alias the ID.

Unit tests pass.