Restore all tests which were previously skipped

New importers:

• RDF
• SKOS

Trello card

Add language attribute

• ComposedOf fields: Trello card
• Modal dialog for field edition: Trello card

Fixes:

• LINK transformer now handle null references
• URI format correctly use another column as label when specified
• Fix JWT token expiration

Trello card

Allow to remove a publication column

Fix front-end webpack build.

Add completes attributes trello

Trello card

Julia does not have to specifiy field names anymore

FIX: Uploaders are now mapped to file extensions