feature request: support webhook

[tianshanghong]

Hi there!

Is it possible to add a webhook request feature that allows the user to set a customized callback URL for Pomodoro? I.e. When a user starts a Pomodoro, the plugin can automatically send GET/POST requests to a callback URL set by the user in config. It will bring users much flexibility and integrate other online services for their Pomodoros.

Imagine that users can utilize this feature and send notifications to their telegram bots, pushover apps, IFTTT services, etc. Users can benefit a lot from this new feature and automate their pomodoro workflows.

[denvey]

That‘s a good idea. Consider joining the next version.