🐛 Fix unix login issue

🐛 Fix check if MariaDB upstream is installed

Fix Ansible min version

Full buster optim (HanXHX#38)

* Remove Stretch and Percona support
* Delete root password management (On Buster, it uses socket auth)
* Fix sync backups files master -> slave
* Cleanup legacy code on replication slave
* Use modern configuration
* Debian buster configuration style
* Drop logrotate management (useless)
* Add new default values in defaults/main.yml (according with MariaDB doc)
* Travis with Ansible 2.8+
* Drop feature "don't replicate mysql database"
* Fully compatible with python3

Support Debian Buster (HanXHX#34)

Fix idempotence fail

/usr/bin/mariadb is not present on upstream builds