Add Twitch button to ECD Tools social banner

Created by: jph152

We'd like to add a button that links to the Cloud Chat Twitch page to the "Stay Connected" banner on https://ecdtools.eclipse.org

Link: https://www.twitch.tv/cloudchat_?hss_channel=tw-1177549444935487488

Twitch logo: https://fontawesome.com/v4.7/icon/twitch