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.   
`reduced_set = [features[int(sf[k])] for k in range(len(sf))]`