Add HTTPS fastcgi param to nginx config template

Allows Django to detect the correct URL scheme
when running with nginx SSL support on.
Required when serving Insight via webstart over HTTPS.
See https://trac.openmicroscopy.org.uk/ome/ticket/10273
Activate nginx HTTPS fastcgi parameter

Should work for both HTTP and HTTPS
on nginx versions 1.1.11 and later.
Revert to conservative nginx https/fastcgi config

Let users amend the configuration based on their
environment to avoid side effects on older nginx setups.
Merge pull request #1469 from zeb/nginx-https-conf-10273-dev-4-4

Include fastcgi https parameter in generated nginx configuration