Fails to build with Ubuntu 16.04

[jspiewak]

The BASE uses ubuntu:latest, now that xenial is released, the build fails compiling some piece with openssl.

[willcode4food]

Upgrading the ngx-openresty version to 1.9.7.2 (latest) seems to resolve this problem. So the Dockerfile on Docker Hub should be updated to

RUN
wget http://openresty.org/download/ngx_openresty-1.9.7.2.tar.gz &&
...