NCBI is in the game

• no longer put blast indices in git, only fasta - need --setupdb before it will work
• new NCBI database: https://www.ncbi.nlm.nih.gov/bioproject/PRJNA313047
• updated bundled CARD, Resfinder
• add --mincov option to filter on coverage
• remove perlisms from the --help output
• improved documentation
• don't barf on empty db folders