make the PHP_UPSTREAM config for NGINX and Apache identical

apache2/Dockerfile

@@ -2,9 +2,10 @@ FROM webdevops/apache:ubuntu-16.04
 
 MAINTAINER Eric Pfeiffer <computerfr33k@users.noreply.github.com>
 
-ARG PHP_SOCKET=php-fpm:9000
+ARG PHP_UPSTREAM_CONTAINER=php-fpm
+ARG PHP_UPSTREAM_PORT=9000
 
-ENV WEB_PHP_SOCKET=$PHP_SOCKET
+ENV WEB_PHP_SOCKET=${PHP_UPSTREAM_CONTAINER}:${PHP_UPSTREAM_PORT}
 
 ENV WEB_DOCUMENT_ROOT=/var/www/public/