supporting proxies

[almugabo]

Great package !
It would be nice to add support for proxies

the request.get method accept proxies (in a form of a dictionary)

 dict_proxies = {'https': 'https://username:password@HOST:PORT',
            'http': 'http://username:password@HOST:PORT',
               }
  requests.get(url , proxies = dict_proxies)