Update setup.py and reqs

It looks like my text editor got a little zealous with the whitespace cleansing. 

Changes: 
* Move version into setup.py and mpld3 out of it. I'm happy to change this back, but I usually try to avoid importing the package itself in the setup file. 
* Try to use setuptools tools with a fallback to distutils. This lets you use ```python setup.py develop``` to make for happy dev times. 
* Add a requirements file and pip install instructions in the Readme. These should be the min reqs required to get running, and in an order that allows for a clean ```pip install -r requirements``` for new users.