gather to opal

Take a gather CSV and one or more NCBI 'accession2taxid' files and create

1. csv containing accessions, taxid
2. csv with lineage

run:

python gather-to-opal.py example_output example_output.csv \
    --acc2taxid nucl_gb.accession2taxid.gz \
    --acc2taxid nucl_wgs.accession2taxid.gz \
    --output example_output.profile