Add publication_date in literature/pubmed_client.py
Add publication_date in literature/pubmed_client.py

Added publication date in function _get_journal_info

bgyori/indra,johnbachman/belpy,bgyori/indra,sorgerlab/belpy,johnbachman/indra,johnbachman/indra,sorgerlab/belpy,sorgerlab/indra,bgyori/indra,johnbachman/belpy,sorgerlab/indra,johnbachman/belpy,sorgerlab/belpy,johnbachman/indra,sorgerlab/indra