Initial commit, list of features:
- /register - Sign up for receiving new issue
- /start - Sign up for receiving new issue
- /unregister - Stop receiving new issue
- /watch ID... - Watch one or multiple issue modification
- /list_watchers - List issue subscription
- /delete_watcher ID... - Delete issue subscription
- /help - Print help message
Instead of user queue we use changestream of mongodb, to notify change of issues. Watch also comments on issue. Add /version command Map /start -> /register