Validation for repeated runs

[mcfrank]

We are considering how to select for a single run for each child in an administration.

One possibility is to have a column called first_valid_administration that is produced by the validator. This would be the first valid_run for that user_id and administration.

This information would be used for a default filter in the R package so users would only get that first valid administration by default but could request all administrations if necessary. Probably we'd want to score all administrations but suppress their scores unless specifically requested.

@mikabr