Run nginx as non-root

Base image is now https://hub.docker.com/r/nginxinc/nginx-unprivileged

Image doesn't have the "official" tag on DockerHub but it's "owned and
maintained by NGINX"

> this image is as "official" as an image without the official images
> tag can be. It's not hosted on the official Docker images library,
> true, but it is owned and maintained by NGINX on both GitHub and
> Docker Hub.

See: nginxinc/docker-nginx-unprivileged#19 (comment)

Part of ticket: https://trello.com/c/x7zhOJ4N/223-run-webapp-as-non-root-not-on-port-80

Dockerfile

@@ -1,4 +1,4 @@
-FROM nginx:stable-alpine
+FROM nginxinc/nginx-unprivileged:stable-alpine
 COPY www /usr/share/nginx/html
 
-EXPOSE 80
+EXPOSE 8080

deploy.json

@@ -3,5 +3,6 @@
     "disable_authentication": false,
     "allowed_ip_ranges": [
       "DOM1"
-    ]
+    ],
+    "port": 8080
   }