Https with certificate

Hi,

It's more a question than a bug.

I'm using _sailsjs_ for a project and i'd like to use a extension to sails named : _sails-rest_. The next version of this extension [v0.1.0-waterline-v0.10](https://github.com/zohararad/sails-rest/tree/v0.1.0-waterline-v0.10) will use _superagent_. It look than **_superagent_ don't support https with certificate authentification**. I had a [discussion](https://github.com/zohararad/sails-rest/issues/63) with the _[Zohararad](https://github.com/zohararad)_ who developed the _sailsjs_ extension, but he asked me to check with you if you can give more information about that issue.

In my project I need to use certificate to authenticate on a API with _sailsjs_. Previously I developed a simple _express_ project and used [request](https://www.npmjs.com/package/request) with a certificate. It worked fine. So why this feature is not implemented in _superagent_, **did you expect to integrate a certificate based authentication**, if it is developed **could you give an example** on how to use it?

Regards,