Normalize broader configurations of `creator`

[iannesbitt]

Issue representing item 2 in this comment in DataONEorg/dataone-indexer#48.

Normalization should be able to handle any definition of creator that is valid SOSO. Broadening the range of definitions able to be normalized correctly would allow for more seamless integration of new repositories using mnlite and potentially enhance the processing of JSON-LD uploaded by end users of DataONE.

[iannesbitt]

Tests can also be run against a broader range of JSON-LD creator configurations in mnlite. Test folder: https://github.com/DataONEorg/mnlite/tree/develop/tests