Changes:
- replaced tornado web app with panel dashboard
- added sequence plot with Bokeh
- added limit kwd to promiscuous_binders
- fix to netmhciipan read_results
- changed cpus to threads kwd
- fixed position value in results dataframe
- improvements to basicmhc1 predictor
- changed cpus to threads kwd
- updated netmhcpan to support 4.1b
- removed refs to Bio Alphabet