Static webGL rendering fix

@greglandrum reply for #257

The code now tries to pull in a local copy; if failure, accesses remote copy on github. Also had to remove some javascript vars.

nbviewer working:

![nbviewer](https://cloud.githubusercontent.com/assets/1449833/3447931/4b987a4e-0153-11e4-928e-7c845bc3cf70.png)

If you have a directory containing `your_notebook.html` and `nbextensions/imolecule.min.js` and run a server, it will find the local library. No problem there. If you're on nbviewer, you need to use a remote copy.

localhost working (with local lib):

![local](https://cloud.githubusercontent.com/assets/1449833/3447950/9a240d40-0153-11e4-89b0-a57b97c0c5d2.png)