Revert "ES6: More controllers converted to ES6"

This reverts commit 23cc7c174a24a5a8d4a1601ec8abfd6cd9e507d8.
Revert "ES6: Half a dozen more controllers converted"

This reverts commit bc2d87e5c1b35bd49e62db944d00cf960b16abd9.
Revert "ES6: Uses proper `normalize` method, includes support for namespaced"

This reverts commit b98324a937f372cfef2295401d180f33e8e6eeb3.
Revert "ES6: `AvatarSelector` and `HeaderController` - also includes support for controllers with"

This reverts commit 44b2f82be84b5fbd316421159859996e1594b850.
Revert "Proof of concept: Load controller via ES6 module in Discourse"

This reverts commit 0327f469c1120d56ac61925424d1e4269b3b8c8c.