Utilize rate limit information from error messages

~/Music $ soundscrape https://soundcloud.com/grrrreatdane/roll-in-peace-bootleg
Downloading: roll in peace (bootleg)
Problem downloading roll in peace (bootleg)
Traceback (most recent call last):
  File "/Users/rjones/anaconda/lib/python3.6/site-packages/soundscrape/soundscrape.py", line 437, in download_tracks
    stream = client.get(track['stream_url'], allow_redirects=False, limit=200)
  File "/Users/rjones/anaconda/lib/python3.6/site-packages/soundcloud/client.py", line 133, in _request
    return wrapped_resource(make_request(method, url, kwargs))
  File "/Users/rjones/anaconda/lib/python3.6/site-packages/soundcloud/request.py", line 148, in make_request
    result.raise_for_status()
  File "/Users/rjones/anaconda/lib/python3.6/site-packages/requests/models.py", line 935, in raise_for_status
    raise HTTPError(http_error_msg, response=self)
requests.exceptions.HTTPError: 429 Client Error: Unknown for url: https://api.soundcloud.com/tracks/377559152/stream?limit=200&client_id=175c043157ffae2c6d5fed16c3d95a4c

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/rjones/anaconda/bin/soundscrape", line 11, in <module>
    sys.exit(main())
  File "/Users/rjones/anaconda/lib/python3.6/site-packages/soundscrape/soundscrape.py", line 119, in main
    process_soundcloud(vargs)
  File "/Users/rjones/anaconda/lib/python3.6/site-packages/soundscrape/soundscrape.py", line 292, in process_soundcloud
    id3_extras=id3_extras)
  File "/Users/rjones/anaconda/lib/python3.6/site-packages/soundscrape/soundscrape.py", line 460, in download_tracks
    puts_safe(e)
  File "/Users/rjones/anaconda/lib/python3.6/site-packages/soundscrape/soundscrape.py", line 1315, in puts_safe
    puts(text)
  File "/Users/rjones/anaconda/lib/python3.6/site-packages/clint/textui/core.py", line 57, in puts
    s = tsplit(s, NEWLINES)
  File "/Users/rjones/anaconda/lib/python3.6/site-packages/clint/utils.py", line 69, in tsplit
    string = string.replace(i, final_delimiter)
AttributeError: 'HTTPError' object has no attribute 'replace'

Start in soundscrape.py at download_tracks around lines 437 and 460, then inspect puts_safe around line 1315 and the handling of the HTTP 429 error shown in the traceback. Determine how rate-limit information should be surfaced or used, and verify that the error no longer produces the secondary AttributeError.