Verify, enrich and export metadata

[nesnoj]

There're some final steps to be done on all the metadata created in the pipeline #450:

• Verify metadata: check metadata (written as table comments) of a predefined list of tables (all which are ticked at Metadata needed? in Create metadata for existing datasets #450).
  • See this issue on how to use OMI from python
  • If something does not comply, should we mark the task failed or throw a warning? (I'd vote for the latter)
• Update / set missing fields
  • id and resources > path (insert URL path to resource on OEP in both, see Clarify path to published tables on OEP #457)
  • publicationDate (now())
• Add internal version no of dataset? (from metadata.datasets)
• Export as JSON to some central place. What about bibtex?