This function returns the mute status of a specific speaker client (host or host:instance).
Parameter: host
Type: string
Description: Leaving this a null string will return the status for the
first instance HomeSeer finds, otherwise use the hostname of the computer
you are interested in determining the listening status of. If
more than one instance of the Speaker application is running on "host"
then you may need to specify the instance as well in the format host:instance.
Return value: mute
status
Type: boolean
Description: TRUE indicates that the speaker app instance is muted.