support http_proxy.
support http_proxy.

ConradIrwin/jist,roxyboy/jist,zmwangx/gist,ConradIrwin/gist,retrography/gist,ryanbradynd05/gist,roxyboy/gist,defunkt/gist,ConradIrwin/gist,mofodox/gist,dLobatog/gist,bchase/gist,eLobato/gist