The following configuration options added:

    galera_innodb_read_io_threads: 8
    galera_innodb_write_io_threads: 8
    galera_wsrep_slave_threads: 8
    galera_xtrabackup_parallel: 4
    galera_error_log_enabled: false

Change-Id: Id1185c3a38669c37dc88806b4e9955522629ce1c
Related-Bug: https://mirantis.jira.com/browse/PROD-16528

This patch removes separate state galera.ssl as it was previously
wrongly introduced. Instead include ssl tasks to master/slave when
ssl is enabled.
This fixes missing requirements when applying separate states.
Ensure that mysql package is installed before changing group
ownership for ssl files to mysql, as group will be added by mysql
packages.

Fix ssl inital configuration. SSL settings are not applied during
service reload, we have to add them during initial galera cluster
start.

Change-Id: Iff9a268000c3e5e722cc6e197cfd223ec1015f73
Related-Prod: PROD-16695

Make max_connections and innodb_buffer_pool_size configurable
through soft params instead of hard.

Change-Id: Id0bb8f6b6091289275864bf4dd6a6890d11b4782

Change-Id: I88e3591eaa018406c48dd790ce946a9f783aa758

Galera master installation hangs on installation
mysql-server-wsrep-5.6. It seems that log_error is not working,
because of next message: "mysqld_safe Can't log to error log and
syslog at the same time. Remove all --log-error configuration
options for --syslog to take effect." Using "syslog = yes" instead
of log_error makes it works without any other changes.

Change-Id: I39a8a87ed048557c19f3843b97c75469385e4978
Closes-bug: PROD-9065