[Docker] Add Javascript kernel to SoS/Docker setup

[mathieuboudreau]

This might allow us to use Plotly.js in blog posts/notebooks, which has more features than than the python version of Plotly, and is usually gets new features first.

I know it's possible to get a Javascript/node.js kernel installed to be used with SoS, because their live sos server link at the end of their homepage has it: http://128.135.144.117:8000/

Possible leads

• sos-javascript Travis file: https://github.com/vatlab/sos-javascript/blob/master/.travis.yml
• IJavascript repo: https://github.com/n-riesco/ijavascript