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

Change-Id: Id0bb8f6b6091289275864bf4dd6a6890d11b4782

Change-Id: Id77cd6da330fe986844b3331edd514819471e67a

The buffer_pool_size parameter should be a integer value when followed
by a memory unit (eg '1024M', not '1024.1M'). Otherwise the MySQL
doesn't start properly.

Change-Id: I5dfad49a8e44a40ae87c5e8e0b033dcd73dc2837

Usage:

  galera:
    master:
      innodb_buffer_pool_size: 1024M
    slave:
      innodb_buffer_pool_size: 1024M

If innodb_buffer_pool_size is not set then 35% of the available
ram will be allocated for the buffer pool.

Change-Id: Iaffa3f5b4ded8bc838f9d707916e360ed873c13b

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