How to get Ionic working behind a proxy? (Error: getaddrinfo ENOTFOUND github.com github.com:443)

I have failed to create an Ionic project using the Ionic CLI. Each time I type
Ionic start project-name gives me this error :

Fetching app base (https://github.com/driftyco/ionic2-app-base/archive/master.tar.gz)
✖ Downloading - failed!
Error: getaddrinfo ENOTFOUND github.com github.com:443

Note that, I am working behind a proxy. npm, git proxies are properly set (atleast I think so) and I can create angular-cli projects without any problem.

Please help me configure proxies properly for Ionic setup. I'm on Windows 7 x64.