First working version of the ispconfig roundcube

- Completly rebuild the container startup to be less brute-forcish
- All relevant configs now lie in the external volume
- DB init is only done if a new config is written.
- ENV Vars are only needed if you want to automatically write a config
- Cleaned up everything

Dockerfile

@@ -54,13 +54,14 @@ RUN set -ex; \
 
 # expose these volumes
 VOLUME /var/roundcube/config
-VOLUME /tmp/roundcube-temp
 
 # Define Roundcubemail version
 ENV ROUNDCUBEMAIL_VERSION 1.3.7
 
-# Publish the rootfs file into the container
-ADD rootfs.tar.gz /
-
+# Set the entry point
 ENTRYPOINT ["/docker-entrypoint.sh"]
 CMD ["apache2-foreground"]
+
+# Finally, publish the rootfs file into the container
+# This is done as last step to make docker build caching more efficient.
+ADD rootfs.tar.gz /