Add support for http webhooks

[arpitgupta]

I had a custom rsync setup that I replaced with this project so that's awesome. I was wondering if we can add support for nfty.sh and/or healthchecks.io to report current status or failure of sync.

If we add the ability to setup custom http/curl webhooks then one can use them to call healthchecks or ntfy or any other notification service one might be using.

[lovelaze]

Hi @arpitgupta

Great suggestion! I definitely agree that this is something we should support