D-Net

#1169 fixing duplicate context issue, introducing integration test proving implemented solution works properly

#1133 dropping useless workfing_dir creation for pig nodes

#919 renaming DocumentToResearchInitiative to DocumentToConceptId and DocumentToResearchInitiatives to DocumentToConceptIds

#963 propagating dataset -> mdstore from import to exporting phase: importer produces DocumentToMDStore datasetore utilized by exporter module. Updating transformer definition to handle DocumentToMDStore instead of Identifier schema

removing memory related properties, fixing #757 should solve all memory related problems

#568 introducing citations grouping by sourceDocumentId, still to be adjusted for ingested pmc citations outcome which currently seems to hang up

#354 removing obsolete transformers/export/person transformer along with tests

#354 removing obsolete transformers/export/inferenced_document_without_imported_data transformer along with tests

#354 removing obsolete transformers/export/identifier/referenceddatasets transformer along with tests

#354 removing obsolete transformers/export/identifier/documents transformer along with tests