This commit allows for more galera/mysql tuning

The change allows the user to change the "mysql_max_connections" as variable
If unset, the default will be (100 * ansible_processor_vcpus). This base value
is determined from information gathered from ansible facts.

This change also modifies the count of wsrep sync thread based on the
the number of CPU cores available on a given host as defined by ansible
facts. This function can also be overriden using the "galera_wsrep_slave_threads"
variable.