Creating refcache per connection breaks "check terms", "check records" per batch

[kspurgin]

Creating the CollectionSpace::Mapper::DataHandler with the refcache created on the connection object caused a bug when you process a batch with {"check_terms": false} in the batch configuration.

I was unable to reproduce the issue within the collectionspace-mapper and therefore couldn't track it down to fix it there.

This commit changed how the DataHandler gets created for a batch, and fixed the bug.

However it relies on offloading the creation of the refcache to collectionspace-mapper, which we probably don't really want to do in production because collectionspace-mapper doesn't know about Redis, etc...