[WIP] Implement new popovers

No issue

Implements a new popover component (not to be confused with what are now called dropdowns [menus])

Todo:

- [x] Emberify
- [ ] Get checked over by people with Über Ember skilz

If I hover the thing, and it opens, I expect clicking it to toggle its state back to closed. If I clicked it to keep it open - there would be no feedback to indicate what had happened - until I moved my mouse away (where I would also expect it to close) and it didn't