Watches a firebase profiler stream for operations that take a long time and report those operations to a slack webhook.

Environment variables:

• FIREBASE_URL - required, *.firebaseio.com
• FIREBASE_AUTH_SECRET - required, the DB's auth key
• SLACK_HOOK - optional, a slack incoming webhook URL to report to
• TIME_THRESHOLD - operations over this number of ms will be reported. Default 5000.