announce online multiplayer matches in Discord

[DreadKnight]

We could eventually integrate the online multiplayer feature with Discord itself, by advertising online matches waiting for players to a specially created channel in our Discord server. This will result in more match-ups and leading to increased player base. There's a JS library with access to the Discord API and also uses npm https://github.com/discordjs/discord.js

Would be handy if the messages on Discord provided links to join the games (provided if logged in or asking to log in and then redirecting). Somewhat related to issue #16