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

vars/Debian-buster.yml

@@ -1,6 +1,5 @@
 mariadb_tools:
-  - percona-toolkit
-  - python-mysqldb
+  - mariadb-backup
   - mysqltuner
-
-mariadb_default_xtrabackup_package: 'percona-xtrabackup-24'
+  - percona-toolkit
+  - python{% if ansible_python_version is version('3', '>=') %}3{% endif %}-mysqldb

vars/Debian-stretch.yml

@@ -1,6 +0,0 @@
-mariadb_tools:
-  - percona-toolkit
-  - python-mysqldb
-  - mysqltuner
-
-mariadb_default_xtrabackup_package: 'percona-xtrabackup-24'