Set command in dockerfile explicitly

Overwrites the command in the base image which specifies "daemon off".
Ensure we're not passing "daemon off" twice, which resultes in an error.

Author: zacblazic

Dockerfile

@@ -58,3 +58,5 @@ COPY ./config/ /etc/nginx/
 STOPSIGNAL SIGQUIT
 EXPOSE 8080
 USER nginx:nginx
+
+CMD ["nginx"]