Sonos WebSocket Edge Driver

@nayelyz

With the latest version of this driver, the mediaGroup commands (groupVolumeUp, groupVolumeDown, muteGroup, unmuteGroup) are doing some funny things. Looking at the code, I saw this, which is a bit of a mess:

[capabilities.mediaGroup.commands.groupVolumeUp.NAME] = CmdHandlers.handle_mute,
[capabilities.mediaGroup.commands.groupVolumeDown.NAME] = CmdHandlers.handle_unmute,
[capabilities.mediaGroup.commands.setGroupVolume.NAME] = CmdHandlers.handle_set_mute,
[capabilities.mediaGroup.commands.muteGroup.NAME] = CmdHandlers.handle_volume_up,
[capabilities.mediaGroup.commands.unmuteGroup.NAME] = CmdHandlers.handle_volume_down,
[capabilities.mediaGroup.commands.setGroupMute.NAME] = CmdHandlers.handle_set_volume,

ETA: Also, the driver is still picking up both Left and Right speakers. When they are paired for stereo, the driver should only pick up the Left speakers—as the old DTH did.