Introduce ApplicationModel for shared code

Leaving model specs duplicated for now.
Revert a bunch of borked code.

Tests passed but coverage wasn't enough to catch some issues. Will
revisit later.

Revert "Introduce ApplicationModel for shared code"

This reverts commit b081ef100fd818348b01ce9a5cf2f164b2129a73.

Revert "JS Commit and Comment .hasAuthor methods"

This reverts commit 116e347685913a8500b2238773d93d1c920f3803.

Revert "Basic Commit JS model"

This reverts commit e32e569f2efecb073b020bd4ffa903eb389d334d.

Revert "Add CurrentUser.name and .isAuthorOf()"

This reverts commit 4e6ed55a28ec9d282573c8728272d5ab0b6ae876.

Revert "Start introducing a CurrentUser service"

This reverts commit 35a4fc37c157ae1d9797ea15ddecf734ce08d1e4.

Revert "Cleanup"

This reverts commit 74e5efb3109863e75ea3bb4b68efefded426e4d0.

Revert "Revert "Cleanup""

This reverts commit 1961dda039a6bc4fad6f6b8125f3249863b2b2ed.