Cleanup Misc Ember Code

No issue

Misc Places
- Removed expired, irrelevant, and fixed todos

FloatingHeaderPartial
- Fixed "Written" vs "Published" text logic

SettingsGeneralController
- Removed single quotes from property names

EditorBaseController, MarkerManagerMixin
- Aligned var declarations

PostItemView
- Commented out unfunctional code for feature request #2398
- Switched `isPage`, `isFeatured` to be computed properties in `Po
- use `toggleProperty` in `PostController.action.toggleFeatured`