Add docstring
Add tests around orgtrello-controller/compute-and-overwrite-card!
Refactor - Use orgtrello-buffer/overwrite-card!
Add tests on orgtrello-controller/--sync-buffer-with-trello-cards!
Refactor - Rename orgtrello-controller/--sync-buffer-with-trello-cards
to orgtrello-controller/sync-buffer-with-trello-cards!
Refactor - Use mapc for side-effects