Syften can now monitor Slack communities

This makes Syften the only social monitoring tool that can do that.

Granted, Slack has a built in option to alert you when certain keywords are mentioned. But what a pain it is to edit those across the 20 different communities you're in. Also, it doesn't allow you to track other users or get alerts when someone replies to your thread.

The feature request came from existing users. Entrepreneural wisdom says to focus on features that get you more users, not those that existing paying customers want, but it was just two days of work so I went for it.