0.6.7

- [X] Create backlog
- [X] Update version
- [X] Improve/Refactor the comment deletion
- [X] Fix `orgtrello-buffer/pop-up-with-content!`
- [X] Improve comment creation - CLOSE https://github.com/org-trello/org-trello/issues/222 [2/2]
  - [X] Add checksum to the comments
  - [X] Improve comment creation
- [X] Release notes