CourseNews
    course              CourseId OnDeleteCascade OnUpdateCascade
    visibleFrom         UTCTime Maybe
    participantsOnly    Bool
    title               Text Maybe
    content             StoredMarkup
    summary             StoredMarkup Maybe
    lastEdit            UTCTime
    deriving Generic
CourseNewsFile
    news     CourseNewsId OnDeleteCascade OnUpdateCascade
    title    FilePath
    content  FileContentReference Maybe
    modified UTCTime
    UniqueCourseNewsFile news title
    deriving Generic