Use NodeJS image for RevealJS

[amouat]

Many thanks for creating the RevealJS Dockerfile.

I've created a new version based on the official NodeJS base image which was recently released. Feel free to grab any of the changes I made: https://github.com/amouat/revealjs-docker.

I didn't fork or submit a pull request as I wanted to have revealjs in its own project rather than as a part of Dockerfiles. Also, I'll probably make more modifications for my own use.

Cheers,

Adrian.