Merge pull request #31 from ardumont/master

Update to latest version
Improve trello-setup explanation regarding M-x
org-trello/install-key-and-token.
Issue that revealed that those information were not apparent - https://github.com/org-trello/org-trello/issues/207
Improve trello setup information
Merge pull request #32 from ardumont/improve-trello-setup-explanation

Improve trello setup information