OO-2967: refactor the list of assessed identities in assessment tools to be delivered by the resource or the course element them self

OO-2897: implement last modification per user role (as participant or as coach), aggregate the values on structure nodes

OO-2790: add the options to upload assessment documents on a per course element / user base which behave like the user comment

OO-1593: implements several strategies for the state "failed", implements done in assessment tool, checklist and group task...

OO-2037: allow coaches and authors to upload and create tasks / solutions in the run view of the group task course element

OO-1761: more fix to the copy of course element within a course, copy or import of a course with a project broker element

OO-1593: return more informations on score evalutation, add a specific persistent assessable course node, fix selenium tests and unit tests