convert tests/bench/tables to hdf5

This was done using 

for i in `find ./ -iname '*biom.gz' `; do python ~/Downloads/convert_to_hdf5.py $i; done
for i in `find ./ -iname '*bench.biom.gz' `; do python ~/Downloads/compare_hdf5.py $i; done

convert_to_hdf5.py 
```python
from __future__ import division

from sys import argv
from biom.parse import parse_biom_table
import h5py
from biom.util import biom_open


def main():
    input_path = argv[1]
    biom_path = input_path[0:-8] + '_hdf5.biom.gz'
    with biom_open(input_path) as t_jsonf:
        t_json = parse_biom_table(t_jsonf)
        f = h5py.File(biom_path, 'w')
        t_json.to_hdf5(f, input_path, compress=True)
        f.attrs['type'] = 'otu table'
        f.close()


if __name__ == "__main__":
    main()
```
compare_hdf5.py
```python
from __future__ import division

from sys import argv
from biom.parse import parse_biom_table
import h5py
from biom.util import biom_open


def main():
    input_path = argv[1]
    input_path = argv[1]
    biom_path = input_path[0:-8] + '_hdf5.biom.gz'
    with biom_open(input_path) as t_jsonf:
        with biom_open(biom_path) as t_hdf5f:
            t_json = parse_biom_table(t_jsonf)
            t_hdf5 = parse_biom_table(t_hdf5f)

            print input_path, t_hdf5 == t_json


if __name__ == "__main__":
    main()
```