Removing double quotes for apache php fpm configuration.

apache2/Dockerfile

@@ -2,7 +2,7 @@ FROM webdevops/apache:ubuntu-16.04
 
 MAINTAINER Eric Pfeiffer <computerfr33k@users.noreply.github.com>
 
-ARG PHP_SOCKET="php-fpm:9000"
+ARG PHP_SOCKET=$PHP_SOCKET
 
 ENV WEB_PHP_SOCKET=$PHP_SOCKET
 

docker-compose.yml

@@ -78,7 +78,7 @@ services:
         build:
             context: ./apache2
             args:
-                - PHP_SOCKET="php-fpm:9000"
+                - PHP_SOCKET=php-fpm:9000
         volumes_from:
             - volumes_source
         volumes: