update to Debian Buster (#253)

* update to Debian Buster
* update webapp container
* update kdav image to buster
  * add some debug commands
* use onbuild to specify building of core repository only in one place
* remove ca-certificates and git from kdav image
  * git should not be needed since kdav has a builder stage
  * ca-certificates is already installed in an earlier stage
* upgrade to Debian 10 for Z-Push
* switch remaining Debian 9 repos in webapp
* use a new major version for the base image
  * since its now based on buster
* add new parameters to the onbuild step
* update repos in setup.sh
* switch default distribution in create repo script

kdav/Dockerfile

@@ -32,18 +32,13 @@ LABEL maintainer=az@zok.xyz \
     org.label-schema.vcs-url="https://github.com/zokradonh/kopano-docker" \
     org.label-schema.schema-version="1.0"
 
-# install Kopano kDAV and refresh ca-certificates
+# install Kopano kDAV
 RUN \
-    # community download and package as apt source repository
-    . /kopano/helper/create-kopano-repo.sh && \
-    if [ ${DOWNLOAD_COMMUNITY_PACKAGES} -eq 1 ]; then \
-        dl_and_package_community "core"; \
-    fi; \
     echo "deb [${KOPANO_REPOSITORY_FLAGS}] ${KOPANO_CORE_REPOSITORY_URL} ./" > /etc/apt/sources.list.d/kopano.list; \
     set -x && \
     apt-get update && apt-get install -y --no-install-recommends \
         apache2 \
-        libapache2-mod-php7.0 \
+        libapache2-mod-php7.3 \
         crudini \
         php7-mapi \
         php-xml \
@@ -51,8 +46,6 @@ RUN \
         php-zip \
         sqlite \
         php-sqlite3 \
-        ca-certificates \
-        git \
         unzip \
         ${ADDITIONAL_KOPANO_PACKAGES} \
     && rm -rf /var/cache/apt /var/lib/apt/lists/*
@@ -70,10 +63,10 @@ RUN \
     echo "Listen 80" > /etc/apache2/ports.conf && \
     # configure mod_php
     a2enmod rewrite && \
-    crudini --set /etc/php/7.0/apache2/php.ini PHP upload_max_filesize 500M && \
-    crudini --set /etc/php/7.0/apache2/php.ini PHP post_max_size 500M && \
-    crudini --set /etc/php/7.0/apache2/php.ini PHP max_input_vars 1800 && \
-    crudini --set /etc/php/7.0/apache2/php.ini Session session.save_path /run/sessions && \
+    crudini --set /etc/php/7.3/apache2/php.ini PHP upload_max_filesize 500M && \
+    crudini --set /etc/php/7.3/apache2/php.ini PHP post_max_size 500M && \
+    crudini --set /etc/php/7.3/apache2/php.ini PHP max_input_vars 1800 && \
+    crudini --set /etc/php/7.3/apache2/php.ini Session session.save_path /run/sessions && \
     mkdir -p /var/lib/kopano/kdav && \
     chown www-data:www-data /var/lib/kopano/kdav && \
     mkdir -p /var/log/kdav && \