added optional use_range_header to webclient's get_stream_audio

#193

I made the header have 3 different options

Default is None: it will try to use the header and if it doesn't work then it will strip the audio.
True: try to use the header and if it doesn't work raise an exception.
False: don't use the header, strip the audio. Same behavior as before.

I dunno if the exception type/text is right, though. might wanna change that later.