InnoDB tables for search indexing where possible

Especially on Galera clusters, search indexing with MyISAM tables will cause
unstable clusters and loss of data. For standalone clusters using MySQL 5.6
or MariaDB 10.0, the database default table storage engine can be used,
since either support fulltext indexing.
Merge pull request #1416 from greezybacon/issue/cluster-search

InnoDB tables for search indexing where possible

Reviewed-By: Peter Rotich <peter@osticket.com>