Remove unused class SearchVariantVersionedDataObject
Remove unused class SearchVariantVersionedDataObject

I added this class for compatibility with silverstripe-fulltextsearch when
integrating these modules for a project. Since SearchVariantVersionedDataObject
is a hacky fix that is only used with a specific configuration of the fulltext
module, it belongs in project code and not in this module.

Resolves #2

heyday/silverstripe-versioneddataobjects,glenn-bautista/silverstripe-versioneddataobjects,glenn-bautista/silverstripe-versioneddataobjects,heyday/silverstripe-versioneddataobjects,tylerkidd/silverstripe-versioneddataobjects,tylerkidd/silverstripe-versioneddataobjects