Add numydoc and script documentation generated by Sphinx

I've restructured the HTML documentation to include a new documentation section:

before:
![screen shot 2014-09-13 at 3 16 37 pm](https://cloud.githubusercontent.com/assets/375307/4262060/4c293e5e-3b8b-11e4-9cf4-44b4b2525709.png)

after:
![screen shot 2014-09-13 at 3 16 31 pm](https://cloud.githubusercontent.com/assets/375307/4262061/54583d28-3b8b-11e4-9ad6-03a93e369691.png)

This section is a generic page of Sphinx docs:
![screen shot 2014-09-13 at 3 18 50 pm](https://cloud.githubusercontent.com/assets/375307/4262065/92126d78-3b8b-11e4-9079-62b2ee91aaf1.png)

The docs include a QIIME-like page for a description of how `make_emperor.py` works and a section that describes the `Emperor` object using the NumPy-doc standard.

Note that I had to add the numpydoc sphinx extension to this project and thus I have added a licenses folder to attribute these projects. I've also added a new line to .travis.yml to check the documentation can be built correctly.

To build the documentation on your own you will need to install `sphinx` and `sphinx-bootstrap-theme`. Once that's done go to the base of the repo and do: `make -C doc html`, then open index.html to see the newly modified homepage that links to the auto-generated documentation.

Fixes #250