create datamodel

[utnapischtim]

it is necessary to create a converter (loader) to convert the receiving xml/json file with the pure metadata structure in a marc21 json object. (connected to #15)

• [ ] loader [pure -> marc21]
  • affiliation -> https://www.loc.gov/marc/bibliographic/bd100.html $u
  • licence -> https://www.loc.gov/marc/bibliographic/bd540.html
  • funder -> https://www.loc.gov/marc/bibliographic/bd536.html
  • peerReview
  • languages
  • abstract
  • authors
  • pages
  • issn/isbn
  • journalName
  • volume
  • issue
  • ...
• [ ] serializer [rdm-records.json -> pure]
• [ ] marshmallow [to validate metadata coming from pure. not all categories are equally important, WIP]