[TASK] Refactored Nginx configuration recipe

The recipe contained firewall stuff we don't need (yet).

The recipe now installs and configures the gitlab site.
[TASK] Refactor Nginx recipe

The recipe now properly places the gitlab site configuration in sites-available.
Then places a symlink into the sites-enabled directory.

It also disables the default site configuration which does nothing.

The location of the socket and the root where modified in the nginx-gitlab site configuration file.