Improved the nginx config to support SSL endpoints

Given the SSL endpoint is handled by heroku, the $https variable needs to be set based on the forwarded proto set by the heroku load balancer.
Removed the explicit disabling of HHTP in symfony2

The HTTPS fastcgi param is set by the default NGinx config since 1.1.11 based on $https.
Merge pull request #105 from stof/patch-2

Improved the nginx config to support SSL endpoints