Pull Request: Add Stationary-Base Demo (2nd attempt)

This PR updates the README.md file to reflect the new Stationary Base addition as well as how to use it.  

It also adds a Stationary Base demo as well as a StationaryBase.js dependency file.  My StationaryBase.js dependency file is located in the newly created 'js' folder.

I changed the dependencies in the script src tags inside my StationaryBaseDemo.html file so that they will go and find the dependencies that are publicly hosted, instead of creating extra copies inside this repository.  These outside dependencies are virtualjoystick.js (which will be found locally in this Master) , three.min.js (which will be found hosted publicly from threejs.org) , and threex.keyboardstate.js (which will be found at jeromeetienne.github.io which is publicly hosted by GitHub).

Thanks!
-Erich