bipy sphinx docs

Basic sphinx documentation area that I demo'd in #86. Depends on sphinx, numpydoc, and sphinx-bootstrap-theme to build the docs. Currently only has docs linked to ```bipy.core.distance``` module. Includes a "Fork me on GitHub" banner (w00t).

I also added a licenses directory to the root of the repo and included the scipy and sphinx-bootstrap-theme licenses. I needed to do this because I copied a couple of files from their sphinx documentation areas.

Once this is merged, I'll hook up the site to readthedocs.org.

Fixes #86.