My first slack bot!

Today I got my Slack bot’s basic features working. /aarav-ping replies with “Pong”, and I also added a reply when the bot is mentioned. I set up the Slack app, added the required permissions, and pushed the code to GitHub.
I tested the code locally and fixed a few setup issues along the way. The bot is not live yet — my next step is to deploy it on Nest, then test the command and mentions in Slack for real.