[Feature] add device for pushover notification

[TylonHH]

Hey,

the pushover notification as descripted here is a nice feature. But I miss the option to specify the receiver of the notofication. Within pushover is set by the "device" tag. I hope this is easy to implement. Otherwise all devices in a pushover account will recieve it.

Here is the doc about pushover (I guess you're familar with it): https://pushover.net/api

kind regards