Review UML Class Diagram

[DavidBlaa]

#14

[geofranzi]

• there is only one source (either of the type Metadata or ...). The current version of the UML diagram shows there is 1 to many and always all types of sources
• several "string" types are an array of entries like "Curator" & "user" (e.g. type of curation entry: Task | Comment)