sorted/mysql: create the db too if it doesn't exist.

Change-Id: I566d49052057848e9d4af0f01243a89db367e20a
sqlkv: remove one of the sql expansion funcs. make batch use KeyValue's

Fixes bug with TablePrefix where batch mutations weren't getting the db prefix.

Change-Id: Ice599e607f070e374471e5ff22b426a6a5e05800