Using SQL as a cache driver is a Bad Idea
[mms] Add factory for Horde_HashTable drivers.
[mms] Horde_Memcache usage is deprecated in favor of Horde_HashTable.
[mms] Add configuration of the Horde_HashTable package.
[mms] Make sure we are not using a SQL Cache driver in the DB object itself.

For obvious chicken/egg reasons.