Information-theoretic subset selection

This new feature adds information theoretic subset selection methods for biological data formats using the [PyFEAST](https://github.com/EESI/PyFeast) module. We have a pull request open, but it was closed several months ago. We have made some adjustments to the code and updated the versioning information as well.   
please change to `import numpy as np`. The order of the imports should conform to PEP8 as well, which is:

python libraries
WHITESPACE
third-party libraries
WHITESPACE
local libraries

What that would look like here is:

```python
from __future__ import division

import numpy as np
from biom.parse import parse_biom_table # note, not accurate with respect to biom 2.1
from cogent.app.util import ApplicationNotFoundError # i believe this should source from burrito?

from qiime.parse import parse_mapping_file_to_dict
```