fix: use native python function to create non-blocking pipe.

Thanks @azlux for this solution. Close #116.

Also created an option 'redirect_ffmpeg_log' to enable/disable
reading the log of ffmpeg.

configuration.default.ini

@@ -105,6 +105,7 @@ password =
 [debug]
 # Set ffmpeg to True if you want to display DEBUG level log of ffmpeg.
 ffmpeg = False
+redirect_ffmpeg_log = True
 mumbleConnection = False
 
 # This is a list of default radio stations.