Standarize image by using shared / similair layers

webmails/roundcube/Dockerfile

@@ -1,9 +1,13 @@
 FROM php:7.2-apache
+#Shared layer between rainloop and roundcube
+RUN apt-get update && apt-get install -y \
+  python3 curl \
+  && rm -rf /var/lib/apt/lists
 
 ENV ROUNDCUBE_URL https://github.com/roundcube/roundcubemail/releases/download/1.3.8/roundcubemail-1.3.8-complete.tar.gz
 
 RUN apt-get update && apt-get install -y \
-      zlib1g-dev curl python3 \
+      zlib1g-dev \
  && docker-php-ext-install zip \
  && echo date.timezone=UTC > /usr/local/etc/php/conf.d/timezone.ini \
  && rm -rf /var/www/html/ \