added additional function that gets controller transport state

Get the current playback state 
        
        Returns:
        A dictionary containing the following information about the speakers playing state
        CurrentTransportState (PLAYING, PAUSED_PLAYBACK, STOPPED), CurrentTrasnportStatus (OK, ?),
        CurrentSpeed(1,?)
        
        This allows us to know if speaker is playing or not. Don't know other states of 
        CurrentTransportStatus,CurrentSpeed