Adding markdown support

[faraazahmad]

Is your feature request related to a problem? Please describe.
The chat doesn't support markdown yet. Sharing code on chat would not be easy to read.

Describe the solution you'd like
It would be better to add markdown support, specifically Github flavoured markdown.

Describe alternatives you've considered
Slack and gitter have a good implementation of markdown support .

Additional context
It would be a small change on the client side, rendering the incoming message as markdown using https://marked.js.org/

[faraazahmad]

@prathambatra