feature(DOCKERFILE): set up nginx to run as non-root

- add libcap
- use setcap (via libcap) to allow nginx to bind to ports <1024
- set permissions on nginx directories
- change nginx pid location to /etc/nginx

build/config/nginx.conf

@@ -2,9 +2,8 @@
 ### NGINX main configuration
 #
 
-user www-docker;
 worker_processes 1;
-pid /var/run/nginx.pid;
+pid /etc/nginx/nginx.pid;
 
 error_log /var/log/nginx/error.log warn;
 
@@ -12,13 +11,13 @@ error_log /var/log/nginx/error.log warn;
 include /etc/nginx/modules/*.conf;
 
 events {
-    worker_connections 512;
+    worker_connections 1024;
     multi_accept off;
     use epoll;
 }
 
 http {
-    server_names_hash_bucket_size 512;
+    server_names_hash_bucket_size 128;
     default_type application/octet-stream;
     charset utf-8;
     include /etc/nginx/mime.types;