metab_network.py and parse_KEGG.py changes
metab_network: use only rare KO's
parse_KEGG.py: added ability to get reactions from reaction_mapformula.lst
metab_network update for reaction_mapformula
Updated metab_network to work with reaction_mapformula.lst to get reactions.  Also made options to use FDR or raw p and ability to say whether file is coming from otu_category_significance.py or group_significance.py.

Changed a function name in parse_KEGG.py