Extract Add MSC, ACM properties to Publication Item

[0surface]

#58

• Add property MSC (Mathematical Subject Classification) to PublicationItem class as string

Sample math & cs subject code API results show no easily discernible pattern to MSC values. For now, they can be persisted & displayed as string.

• Add Propert ACM (Association of Computing Machinery Classification) to PublicationItem as string

• Add logic to set as list when subject code is not found in static list (fetched and provided to Transform Service)