Implemented treating assignees and responsibles differently so there
are no (non-functional) group responsibles anymore
Removed old timelines helper for getting available responsibles
to unify ordering for possible assignees and responsibles on work_package
edit
Merge remote-tracking branch 'origin/dev' into fix/remove_group_responsibles
Adds changelog entry
Merge pull request #856 from opf/fix/remove_group_responsibles