Have all later docs processing commands record submitted date

[ondrae]

We know if later docs are submitted by looking for a submitted at date on the dashboard. Our commands to process and submit these documents should record this date, so we dont need to do it manually.

Its one more step before automating them.

When we mark as submitted, we do:

    @later_document_submitter = LaterDocumentSubmitter.find(later_document_submitter_id)
    @later_document_submitter.update({ submitted_to_county_at: Time.zone.now })
    @later_document_submitter.save

[ondrae]

This got posted in the health repo accidentally because Waffle is waffle.