Add in-container nextcloud install

This increases the size of the container image, but reduces the reliance
on the external volume for loading application data. This couples the application
code to the container image rather than to the container state.

php-fpm/Dockerfile

@@ -64,6 +64,11 @@ COPY ./php.ini-production /usr/local/etc/php/php.ini
 # Set the working directory
 WORKDIR /var/www/html
 
+RUN curl -sSLo latest.zip https://download.nextcloud.com/server/releases/latest.zip
+RUN unzip latest.zip
+RUN rm latest.zip
+RUN chown -R www-data:www-data nextcloud/
+
 # Expose port 9000 for PHP-FPM
 # EXPOSE 9000