Support "dev" as validation set name

To respect our naming convention at Teklia.

Refs https://redmine.teklia.com/issues/8739

We will remove support for validation name. Please update the documentation as well.

changed milestone to %Backlog

added P2 label

assigned to @ebardou

changed the description

mentioned in merge request !118 (merged)

mentioned in commit bc570681

closed with merge request !118 (merged)

mentioned in issue arkindex/doc#148 (closed)