Observer targetActions follow paths

When setting observers with targetActions inside a Route's event hash
the targetAction function was not being properly called.

example:

```js
App.NewRecordRoute = Ember.Route.extend({
  events: {
    submit: function() {
      this.controller.get('content').addObserver('id', this, 'afterCreate');
      this.controller.get('strore').commit();
    },
    afterCreate: function() {
      this.controller.get('content').removeObserver('id', this, 'afterCreate');
    }
  }
});
```