Fixed get_ncbi_pubmed script: identifier -> primaryIdentifier.
Fixed get_ncbi_pubmed script: identifier -> primaryIdentifier.



Former-commit-id: cb7d4840af6d40cfedbc952b877c8349161f5439
julie-sullivan/phytomine,julie-sullivan/phytomine,julie-sullivan/phytomine,julie-sullivan/phytomine,julie-sullivan/phytomine,julie-sullivan/phytomine,julie-sullivan/phytomine