Full buster optim (#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

tasks/secure.yml

@@ -1,16 +1,5 @@
 ---
 
-- name: MYSQL_USER | Update mysql root password for all root accounts
-  mysql_user:
-    name: root
-    host: "{{ item }}"
-    password: "{{ mariadb_root_password }}"
-  loop:
-    - "{{ ansible_hostname }}"
-    - 127.0.0.1
-    - ::1
-    - localhost
-
 - name: MYSQL_USER | Remove all anonymous users
   mysql_user:
     name: ''