Add library & example for interactive network visualization

[tylere]

Options:

• bokeh - Interactive Web Plotting for Python. Has some support for Graph and Network plots. (Already installed as part of the Jupyter stacks image)
• networkx - NetworkX is a Python package for the creation, manipulation, and study of the structure, dynamics, and functions of complex networks. (Already installed as part of the Jupyter stacks image)
• visJS2jupyter - a tool to bring the interactivity of networks created with vis.js into jupyter notebook cells. Network examples.
• graphviz - simple pure-Python interface for the Graphviz graph-drawing software.
• pygraphistry - PyGraphistry is library to extract, transform, and visually explore big graphs