updated nginx configuration to allow wildcard https redirects

Hello,

I setup a blog using Ghost on my personal server, hosted at `blog.example.com`.
With the current configuration, if I go to `http://blog.example.com`, I get redirected to `https://sandstorm.example.com` instead of `https://blog.example.com`

I found [this stackoverflow post](http://serverfault.com/questions/447258/redirect-wildcard-subdomains-to-https-nginx), and it allows for the blog to be redirected properly.

note, this prevents `someurl.example.com` from being redirected to `sandstorm.example.com`

Please tell me if there is something that can be improved with my pull request, I'm still new at this