added KEGG Pathways metadata

fixes #46. md5sum is 

891bf2b4433e63444a0b5f7d8ec71a79  ko_precalculated.biom.gz

Pathways obtained by the cogent parsers, essentially Greg's earlier link. Note, the table is slightly smaller but I'm not completely sure why. However, the BIOM 1.1.1 formatter was improved from BIOM 1.0 and it is possible that accounts for the size difference.

I have not run this through BIOM but have done preliminary sanity checks on the table and AFAIK it is sane.