fix(select): Fix several issues when moving options between groups

* When an option was moved to a previous group, the group that loose the option would remove the label from the controller
* When an entire option group was removed, the options in the group were mot removed from the controller
agree that it would be nicer, but right now controllers are only exposed as
`$element.data('$' + directive.name + 'Controller', controllerInstance.instance)`