Fixes #3142 : Display rollbacked events

this is linked to http://www.rudder-project.org/redmine/issues/3142

the main goal is to improve the rollback feature.

- Adding a rollback event log  With this event be able to look for and track rollbacked event. #3143
- Add th epossibilit to rollback "ImportsX" and "Rollback". #3144