[Feature] Disable playback share only for specific apps #124

Is your feature request related to a problem? Please describe.
Spotify already shares what's playing between devices, so airsync just duplicates it and makes it more confusing

Describe the solution you'd like
The ability to exclude specific apps, from the macOS side and the android side, to not share now playing status

Describe alternatives you've considered
I'm not sure if Spotify share can be disabled, but it's also more responsive than airsync's so I prefer it