Summary
1. Add support for WebhookClient
2. Add `is_debug`, which is helpful when running locally
3. Set limits for traceback and message according to [https://api.slack.com/docs/rate-limits](Slack Rate Limits)
4. Add username to the original message (WebhookClient doesn't support sending as user)
5. Update tests
**Full Changelog**: https://github.com/s3m3dov/logging_slacker/commits/v0.1.0