BUG: Pass file path to convert_biom_to_table

This function did not deal well with file like objects now that HDF5 is
a supported format, internally changing convert_biom_to_table to use
biom.load_table fixes this problem.

Fix #1598
Merge pull request #1599 from ElDeveloper/supervised-learning-hdf5

BUG: Pass file path to convert_biom_to_table
Merge branch 'master' of https://github.com/biocore/qiime into add-sumaclust

pulling latest updates
pep8 compliant