Added crontab support and switched to MariaDB

[KG7QIN]

A few changes were made:

• Switched from MySQL to MariaDB
• Added support for crontab with the ability to change the crontab file and restart the container for the changes to take effect.

I also changed how this is built. By default now it uses docker-compose to build the container. This was done to support the changes that I made and allow the ability to update the contab file in the config directory and restart the container for the changes to take effect.

An entrypoint.sh file was added. This file will wait 90 seconds for MariaDB to be ready and either continue with initialization or quit. Once MariaDB is ready, the script will then start the cron service then execute the default entry point of docker-php-entrypoint with the argument of apache2-foreground, which starts Apache and PHP.

Additionally the database is now persistent across container rebuilds. Data from MariaDB is now kept in db_data/mysql.

[leleobhz]

It's possible to keep phpIpam image the way it was and use a docker-friendly scheduler service. I've suggested to use cron from Ofelia at #77 (comment)