Improve log management (#27)

* New log management (see #25)

- Add logrotate (as optional feature) setup
- Delete obsolete log management (log + log_slow_queries)

* Change log path

defaults/main.yml

@@ -8,6 +8,7 @@ mysql_vendor: 'mariadb'
 mysql_root_password: 'change_me_NOW'
 mysql_notify_restart: true
 mysql_upstream_apt_src: false
+mysql_manage_logrotate: true
 
 # -------------------------------------
 # Configuration
@@ -25,7 +26,7 @@ mysql_socket: '/var/run/mysqld/mysqld.sock'
 
 # Slow query log settings.
 mysql_slow_query_log_enabled: false
-mysql_slow_query_log_file: '/var/log/mysql-slow.log'
+mysql_slow_query_log_file: '/var/log/mysql/mysql_slow.log'
 mysql_slow_query_time: 2
 
 # Memory settings (default values optimized ~512MB RAM).
@@ -57,8 +58,7 @@ mysql_innodb_lock_wait_timeout: 50
 mysql_mysqldump_max_allowed_packet: '64M'
 
 # Logging settings.
-mysql_log: ''
-mysql_log_error: '/var/log/mysql.err'
+mysql_log_error: '/var/log/mysql/mysql_error.log'
 mysql_syslog_tag: 'mysql'
 
 # -------------------------------------