Nginx support

[Me.B]

We could also add opcache & apc cache enable/disable per site, I think that would apply in apache/nginx.

I've tested already in apache enable disable gzip per website. worked fine.

On nginx we will need php-fpm, wich will imply we may be able to set a php.ini per user/site.

I will for sure release an alpha implementation of nginx for testing and feedback later, before we it get even implemented in sentora.