Improve the messaging experience by adding a new subtype. This allow users to subscribe or not to to Git Commits.
General refactor to make the code testable and to support gitlab and github webhook. Also add testcases to avoid regression and ease testing.
Rename the field 'task_code' to 'code' to ease transition to project_task_code in OCA repo.
When using multiple database, we need some tweak to make it work as system wide module. Otherwise the hook is not register an nothing happen.