Reactions demo

[timkinnane]

Complete Rocket.Chat adapter demo with a demonstration of reactions using text, custom and NLU listeners.

• Use https://github.com/omnidan/node-emoji to match any emoji key
• Add middleware parsing actual emoji in strings into their key
• Use sentiment middleware (or draft NLU adapter) to get sentiment if unmatched and react with 😐, 😄 or ☹️

See https://github.com/Amazebot/bbot/blob/master/src/demo/rocketchat.ts