Modernize web app infrastructure for the demo

Bump glob-parent from 5.1.1 to 5.1.2 in /demo

Bump hosted-git-info from 2.8.8 to 2.8.9 in /demo

Bump lodash from 4.17.15 to 4.17.21 in /demo

Bump path-parse from 1.0.6 to 1.0.7 in /demo

Demo: Clarify README.md

Reorganize README.md

Demo: Run `npm i`

Demo: Run `jspm map ./src/index.js -o importmap.json`

Demo: Use system.js loader to support all browsers, not just Chrome

Demo: Run `jspm install loglevel`

Demo: Run `jspm install minnie-janus`

Demo: Run `jspm install webrtc-adapter`

Demo: Run `npm i -D systemjs systemjs-transform-babel`

Demo: Run `npm i`