bumped version to 2.4.0
updated release date
Merge pull request #497 from xliiv/bumped-version

bumped version to 2.4.0
fixed initial licences in user form and related name in ``LicenceUser`` model
Merge remote-tracking branch 'origin/release/2.4.0' into develop
Merge pull request #500 from ar4s/fix-licence-user-related-name

Fixed related name in ``LicenceUser`` model