fix apt install errors on webserver

docker/templates/web-server-Dockerfile

@@ -5,7 +5,9 @@
 FROM php:{{APP_PHP_VERSION}}-apache
 
 # install packages
-RUN apt-get update && apt-get install -y {{APP_APT_PACKAGES}}
+RUN apt-get update && rm -rf /var/lib/apt/lists/* 
+RUN mkdir -p /var/cache/apt/archives/partial
+RUN apt-get install -y {{APP_APT_PACKAGES}}
 
 # enable apache modules
 RUN a2enmod {{APP_APACHE_MODULES}}