Use TuneBox as a generic cast device

[soehlert]

It would be awesome if we could somehow cast using TuneBox, using the TuneBox machine as a relay for playing to other network-based players (chromecast, airplay, etc). Plex currently is able to cast to Google Play devices and I see support for Sonos in the python-plexapi library itself. It's unclear if we can access the casting abilities of Plexamp and also I have no idea how to try this for Airplay.

[soehlert]

Could maybe look at integrating pychromecast for Google chrome casting. For Airplay we could look at pyatv