Disable mariadb query-cache to resolve deadlocks

...plication-cluster-multi-master/galera/getting-started-with-mariadb-galera-cluster/

Disabling query_cache (and setting size to 0M so it doesn't allocate the RAM)
This is a huge reason for seeing deadlocks with Galera, hence the mandatory turning off

Addresses #143 

(cherry picked from commit 5cecca96824b992a93140ae65838b95d5e658232)