I believe this pull request adds a useful functionality: ability to add nginx customization for both locations.

I needed this because when you use add_header in a location block in Nginx, it undoes all "parent" add_header directives.
So the current server customization is not enough if headers need to be added for all the pages.

In my use case scenario I need to add x-robots-tag for all the pages to disallow search engines to crawl the website in a staging environment.

This should also close #33