changed parse_reaction_mapformula_cos method name to reflect what method does
add parse_picrust_KO_table.py

new function to get information from picrusts ko table such as lists of ko's per otu. Currently not functional.
add new function filter_KOs_by_pathway.py

takes in a biom table of KOs and filters it to only contain the KOs of a single pathway or a list of pathways