* README update
* Remove useless legacy files
* Small refactoring for Galera Cluster
* Modern Ansible
* Some changes on travis + Vagrant
* Help debug: display all facts
* Fix galera config for docker
- Support Debian Stretch (MariaDB debian/upstream + Galera)
- Doc updated
- New travis tests (with Vagrant)
- Drop support of mysql_innodb_additional_mem_pool_size
- Xtrabackup optionnal installation + package name updatable
- Fix many issues with replication (Ansible 2.3)
- Auto-retreive master IP address on tests
- MySQL tools per OS release