Report total download time when finished

chanarch.py (__main__):
  - Show total download time when all threads have been downloaded
Use timeout on connections

chanarch.py:
  - Remove unused urllib imports

chanarch.py (ChanThread):
  - Replace jsonurl with JSON server and server path for easier usage

  __init__():
    - Accept and set a timeout argument

  set_thread():
    - Create the JSON URL as server and server path components, rather
      than a single URL string

  update_info():
    - Use httplib/http.client for connections
    - Use timeout in connections

  download_files():
    - Pass timeout to Downloader

chanarch.py (Downloader):
  - Add timeout to connections

chanarch.py (__main__):
  - Accept --timeout TIMEOUT argument