Merge branch 'hotfix/1.2.5'

Fixes:
- Rendering error of JudgementForm when Submission has no language set
- Deletion of Judgement that was never saved (e.g. empty Judgement on
  first save)
- Event-based filtering in submission listing
Update version number and changelog
Merge branch 'release/1.3'
Fix wrong license reference and update footer
Fix lesson tutor listing
Merge branch 'hotfix/1.3.1' into develop
Merge branch 'develop' of github.com:moschlar/SAUCE into develop