Implement new popovers

No issue

Implements a new popover component (not to be confused with what are now called dropdowns [menus])

Todo:

- [x] Emberify
- [x] Get checked over by people with Über Ember skilz
- [ ] Remove temporary code in debug view (when the rest of the code is all good)

If the name bugs you, you can always change it from "dropdown" everywhere to .. "popDropAndLock" or something as fitting