Set date_created on versions

[carolyncole]

When migrating we are storing the date the version was originally created in the date_created predicate. This property should also be set on creation by Hydra::Works::UploadFileToFileSet to the current time, so that the UI can just display one value not need to look at both date_created and created property.

[jrgriffiniii]

This looks to have been specific to Sufia/CurationConcerns rather than hydra-works.

[jrgriffiniii]

After investigating https://github.com/samvera/hydra-works/blob/master/lib/hydra/works/services/add_file_to_file_set.rb, I suspect that I was mistaken. This may still be a valid proposal.