added seterr to raise on divide
removed unused import
Port subsample function
Merge pull request #191 from wasade/seterr

Seterr
Merge branch 'master' into subsample

Conflicts:
	doc/source/index.rst
improve docstrings based on @ElDeveloper's comments
added Raises section

Thanks @ElDeveloper and @gregcaporaso, you two are bros.
Merge pull request #193 from ElBrogrammer/subsample

Port subsample function
Merge branch 'master' of https://github.com/biocore/scikit-bio into issue_168

Conflicts:
	skbio/maths/stats/test.py