Support HTTPS_PROXY as well
Support HTTPS_PROXY as well

closes #42

defunkt/gist,Jwata/gist-old,flores/gist,ConradIrwin/gist,bchase/gist,ConradIrwin/gist,ryanbradynd05/gist,zmwangx/gist,mofodox/gist,dLobatog/gist,retrography/gist,roxyboy/gist,ConradIrwin/jist,mattn/gist,roxyboy/jist,eLobato/gist