nginx: add modules?

[pexcn]

• [ ] https://github.com/arut/nginx-dav-ext-module (https://github.com/heiher/nginx-dav-ext-module)
• [ ] https://github.com/leev/ngx_http_geoip2_module
• [ ] https://github.com/ngarratt/nginx_upstream_check_module/tree/zenedge-merge (SSL Support?)