The old mechanism of card/checklist/items regarding the checklist may
become obsolete as http://orgmode.org/manual/Checkboxes.html is way better!
- [X] Use the native org checklist to sync to trello [3/3]
  - [X] Extract the informations from the checklist and item and plug them in the current synchronization (org-entry-get (point) "orgtrello-id")
  - [X] Set the metadata information on the checklist level (org does only the heading level)
  - [X] Ensure the synchronization works