start of pip setup

DO NOT MERGE YET.

Issuing pull request to address #220. However, there are a few points of discussion:

* we currently import test numpy in ``setup.py``, this breaks "pip install" in a fresh environment. I think the correct approach is to pull out dependency checks and push them into ``biom.__init__``
* pyqi needs to be in pip
* I stubbed out for nosetests and tox, thoughts?