Simple bot that interacts with Mopidy.

Configured through the following environment variables:

• SLACK_BOT_CHANNEL - Channel that songs being played are posted in
• SLACK_BOT_WS_URL - Mopidy WebSocket URL
• SLACK_BOT_TOKEN - Slack app signing secret
• SLACK_BOT_TOKEN - Slack app bot token
• SLACK_BOT_PORT - Port for bot to listen on