Galera replication of events is not consistent

Refs: https://bugs.launchpad.net/codership-mysql/+bug/1312618 https://jira.percona.com/browse/PXC-999

MariaDB Galera has following problems based on mtr testing:

• After SST from master node (the one where event is ENABLED) - you will end up with the event enabled on two nodes, hence it's now being executed twice. It can be solved by comparing event's originator with server_id. if not equal, then change its status to 'SLAVESIDE_DISABLED'

• If event owner node is re-created using SST, all the nodes have the event now in "SLAVESIDE_DISABLED" state, hence manual action is needed to re-enable the event on one of the nodes. This requirement of the manual action will be documented.