Added create_static method to Scene class. It allows you to create

static webpages for the visualization.
Added cleanup_static method to remove the static data generated!

###To test this branch..###
modify last line in <code>pydy_examples/illustrative_example_for_viz/illustrative_example.py</code>
from:
<code> scene.display()</code>
to:
<code> scene.create_static()</code>
and run it:
<code> python illustrative_example.py</code>

then cd to static directory generated, and from terminal
<code>$ python -m SimpleHTTPServer</code>
You should be able to see visualization at localhost:8000