Create Tags Management Stubs for Ember

closes #4260

- Adds "tags" route inside of the settings routes.
- Adds this route to router.js
- Links the route from the settings.hbs template
- Adds demo tags html in tag.hbs template
- Adds flag for tagsUI
Ewww, is this really how we're doing that? Haha, I see a potential beginner issue.. move this data-config stuff up to metas