Snyk and Gitter for Parallel.js

[MaXFalstein]

#161 - Updated the badges within the README.

I think we should add snyk.io and Gitter.im.
The badge code is already in the README but is commented.

[![Known Vulnerabilities](https://snyk.io/test/github/parallel-js/paralle.js/badge.svg)](https://snyk.io/test/github/parallel-js/paralle.js)

[![Join the chat at on Gitter.im](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/parallel-js/parallel.js)

[amilajack]

We should do this. +1